diff --git a/src/fragmentarium/domain/Date.ts b/src/fragmentarium/domain/Date.ts
index 31002b454..186b3a211 100644
--- a/src/fragmentarium/domain/Date.ts
+++ b/src/fragmentarium/domain/Date.ts
@@ -154,18 +154,20 @@ export class MesopotamianDate {
     const year = parseInt(this.year.value)
     const month = parseInt(this.month.value)
     const day = parseInt(this.day.value)
-    return this.isSeleucidEra === true
-      ? this.seleucidToModernDate(year, month, day)
-      : this.king?.orderGlobal &&
-        Object.values(data.rulerToBrinkmanKings).includes(
-          this.king?.orderGlobal
-        )
-      ? this.nabonassarEraToModernDate(year, month, day)
-      : this.isAssyrianDate && this.eponym?.date
-      ? `ca. ${this.eponym?.date} BCE`
-      : this.king?.date
-      ? this.kingToModernDate(year)
-      : ''
+    let result = ''
+    if (this.isSeleucidEra) {
+      result = this.seleucidToModernDate(year, month, day)
+    } else if (
+      this.king?.orderGlobal &&
+      Object.values(data.rulerToBrinkmanKings).includes(this.king?.orderGlobal)
+    ) {
+      result = this.nabonassarEraToModernDate(year, month, day)
+    } else if (this.isAssyrianDate && this.eponym?.date) {
+      result = `ca. ${this.eponym?.date} BCE`
+    } else if (this.king?.date) {
+      result = this.kingToModernDate(year)
+    }
+    return result
   }
 
   private seleucidToModernDate(
diff --git a/src/fragmentarium/domain/DateConverter.ts b/src/fragmentarium/domain/DateConverter.ts
index 63171560b..491adf6af 100644
--- a/src/fragmentarium/domain/DateConverter.ts
+++ b/src/fragmentarium/domain/DateConverter.ts
@@ -1,51 +1,9 @@
 import data from 'fragmentarium/domain/dateConverterData.json'
-import _ from 'lodash'
-
-interface CalendarProps {
-  year: number
-  bcYear?: number
-  month: number
-  day: number
-  weekDay: number
-  cjdn: number
-  lunationNabonassar: number
-  seBabylonianYear: number
-  seMacedonianYear?: number
-  seArsacidYear?: number
-  mesopotamianMonth: number
-  mesopotamianDay?: number
-  mesopotamianMonthLength?: number
-  ruler?: string
-  regnalYear?: number
-}
-
-interface CalendarUpdateProps {
-  year: number
-  month: number
-  day: number
-  weekDay: number
-  cjdn: number
-  seBabylonianYear: number
-  lunationNabonassar: number
-  mesopotamianMonth: number
-  regnalYear: number
-  i: number
-  j: number
-}
-
-export default class DateConverter {
-  calendar: CalendarProps = {
-    year: 0,
-    month: 0,
-    day: 0,
-    cjdn: 0,
-    weekDay: 0,
-    mesopotamianMonth: 0,
-    seBabylonianYear: 0,
-    lunationNabonassar: 0,
-  }
+import DateConverterBase from 'fragmentarium/domain/DateConverterBase'
 
+export default class DateConverter extends DateConverterBase {
   constructor() {
+    super()
     this.setToModernDate(-310, 3, 3)
   }
 
@@ -127,175 +85,4 @@ export default class DateConverter {
     )
     this.setFromCjdn(cjdn)
   }
-
-  private setFromCjdn(cjdn: number): void {
-    const [year, month, day] = this.computeModernDateFromCjnd(cjdn)
-    this.applyModernDate({ year, month, day })
-    this.updateBabylonDate(cjdn)
-  }
-
-  private computeCjdnFromSeBabylonian(
-    seBabylonianYear: number,
-    mesopotamianMonth: number,
-    mesopotamianDay: number
-  ): number {
-    const i = this.findIndexInSeBabylonianYearMonthPeriod([
-      seBabylonianYear,
-      mesopotamianMonth,
-    ])
-    return data.babylonianCjdnPeriod[i] + mesopotamianDay - 1
-  }
-
-  private findIndexInSeBabylonianYearMonthPeriod(
-    yearMonth: [number, number]
-  ): number {
-    const i = data.seBabylonianYearMonthPeriod.findIndex((ym) =>
-      _.isEqual(ym, yearMonth)
-    )
-    if (i === -1)
-      throw new Error('Could not find matching Babylonian date in data.')
-    return i
-  }
-
-  private computeModernDateFromCjnd(cjdn: number): [number, number, number] {
-    const b = cjdn + 1524
-    const c = Math.floor((b - 122.1) / 365.25)
-    const d = Math.floor(365.25 * c)
-    const e = Math.floor((b - d) / 30.6001)
-    const day = b - d - Math.floor(30.6001 * e)
-    const month = e < 14 ? e - 1 : e - 13
-    const year = month > 2 ? c - 4716 : c - 4715
-    return [year, month, day]
-  }
-
-  updateBabylonDate(
-    cjdn: number = this.computeCjdnFromModernDate(
-      this.calendar.year,
-      this.calendar.month,
-      this.calendar.day
-    )
-  ): void {
-    const weekDay = this.computeWeekDay(cjdn)
-    const [
-      i,
-      lunationNabonassar,
-      seBabylonianYear,
-      mesopotamianMonth,
-    ] = this.computeBabylonianValues(cjdn)
-    const [j, regnalYear] = this.computeRegnalValues(seBabylonianYear)
-    this.updateCalendarProperties({
-      year: this.calendar.year,
-      month: this.calendar.month,
-      day: this.calendar.day,
-      cjdn,
-      weekDay,
-      lunationNabonassar,
-      seBabylonianYear,
-      mesopotamianMonth,
-      regnalYear,
-      i,
-      j,
-    })
-  }
-
-  private computeCjdnFromModernDate(
-    year: number,
-    month: number,
-    day: number
-  ): number {
-    return (
-      Math.floor(365.25 * (month < 3 ? year - 1 : year + 4716)) +
-      Math.floor(30.6001 * (month < 3 ? month + 12 : month + 1)) +
-      day -
-      1524
-    )
-  }
-
-  private computeWeekDay(cjdn: number): number {
-    return ((cjdn + 1) % 7) + 1
-  }
-
-  private computeBabylonianValues(
-    cjdn: number
-  ): [number, number, number, number] {
-    const i = data.babylonianCjdnPeriod.findIndex((cjdnPd) => cjdnPd > cjdn)
-    const [
-      seBabylonianYear,
-      mesopotamianMonth,
-    ] = data.seBabylonianYearMonthPeriod[i - 1]
-    return [i, 1498 + i, seBabylonianYear, mesopotamianMonth]
-  }
-
-  private computeRegnalValues(seBabylonianYear: number): [number, number] {
-    const j = data.rulerSeYears.findIndex((year) => year > seBabylonianYear)
-    return [j, seBabylonianYear - data.rulerSeYears[j - 1] + 1]
-  }
-
-  private calculateYearOffset(currentMonth: number, offset: number): number {
-    return currentMonth + offset > 12 ? 1 : currentMonth + offset < 1 ? -1 : 0
-  }
-
-  private calculateNewMonth(currentMonth: number, offset: number): number {
-    return ((currentMonth + offset + 11) % 12) + 1
-  }
-
-  updateCalendarProperties(props: CalendarUpdateProps): void {
-    const { cjdn, weekDay, year, month, day } = props
-    this.calendar.cjdn = cjdn
-    this.calendar.weekDay = weekDay
-    this.applyModernDate({ year, month, day })
-    this.applyBabylonianDate(props)
-    this.applySeleucidDate(props)
-  }
-
-  private applyModernDate({
-    year,
-    month,
-    day,
-  }: Pick<CalendarProps, 'year' | 'month' | 'day'>): void {
-    this.calendar = {
-      ...this.calendar,
-      year,
-      month,
-      day,
-      bcYear: year < 1 ? 1 - year : undefined,
-    }
-  }
-
-  private applyBabylonianDate(props: CalendarUpdateProps): void {
-    const { cjdn, seBabylonianYear, mesopotamianMonth, i, j } = props
-    const mesopotamianDay = cjdn - data.babylonianCjdnPeriod[i - 1] + 1
-    const mesopotamianMonthLength =
-      data.babylonianCjdnPeriod[i] - data.babylonianCjdnPeriod[i - 1]
-    const ruler = seBabylonianYear < 161 ? data.rulerName[j - 1] : undefined
-    const regnalYear = seBabylonianYear - data.rulerSeYears[j - 1] + 1
-    const lunationNabonassar = 1498 + i
-    this.calendar = {
-      ...this.calendar,
-      mesopotamianDay,
-      mesopotamianMonthLength,
-      mesopotamianMonth,
-      ruler,
-      regnalYear,
-      lunationNabonassar,
-    }
-  }
-
-  private applySeleucidDate(props: CalendarUpdateProps): void {
-    const { seBabylonianYear, mesopotamianMonth } = props
-    const seMacedonianYear =
-      seBabylonianYear > 0 && mesopotamianMonth < 7
-        ? seBabylonianYear
-        : seBabylonianYear > -1 && mesopotamianMonth > 6
-        ? seBabylonianYear + 1
-        : undefined
-    const seArsacidYear =
-      seBabylonianYear >= 65 ? seBabylonianYear - 64 : undefined
-    this.calendar = {
-      ...this.calendar,
-      seBabylonianYear,
-      seMacedonianYear,
-      seArsacidYear,
-    }
-  }
 }
diff --git a/src/fragmentarium/domain/DateConverterBase.ts b/src/fragmentarium/domain/DateConverterBase.ts
new file mode 100644
index 000000000..5b12d1982
--- /dev/null
+++ b/src/fragmentarium/domain/DateConverterBase.ts
@@ -0,0 +1,218 @@
+import data from 'fragmentarium/domain/dateConverterData.json'
+import _ from 'lodash'
+
+export interface CalendarProps {
+  year: number
+  bcYear?: number
+  month: number
+  day: number
+  weekDay: number
+  cjdn: number
+  lunationNabonassar: number
+  seBabylonianYear: number
+  seMacedonianYear?: number
+  seArsacidYear?: number
+  mesopotamianMonth: number
+  mesopotamianDay?: number
+  mesopotamianMonthLength?: number
+  ruler?: string
+  regnalYear?: number
+}
+
+interface CalendarUpdateProps {
+  year: number
+  month: number
+  day: number
+  weekDay: number
+  cjdn: number
+  seBabylonianYear: number
+  lunationNabonassar: number
+  mesopotamianMonth: number
+  regnalYear: number
+  i: number
+  j: number
+}
+
+export default class DateConverterBase {
+  calendar: CalendarProps = {
+    year: 0,
+    month: 0,
+    day: 0,
+    cjdn: 0,
+    weekDay: 0,
+    mesopotamianMonth: 0,
+    seBabylonianYear: 0,
+    lunationNabonassar: 0,
+  }
+
+  setFromCjdn(cjdn: number): void {
+    const [year, month, day] = this.computeModernDateFromCjnd(cjdn)
+    this.applyModernDate({ year, month, day })
+    this.updateBabylonDate(cjdn)
+  }
+
+  applyModernDate({
+    year,
+    month,
+    day,
+  }: Pick<CalendarProps, 'year' | 'month' | 'day'>): void {
+    this.calendar = {
+      ...this.calendar,
+      year,
+      month,
+      day,
+      bcYear: year < 1 ? 1 - year : undefined,
+    }
+  }
+
+  computeCjdnFromSeBabylonian(
+    seBabylonianYear: number,
+    mesopotamianMonth: number,
+    mesopotamianDay: number
+  ): number {
+    const i = this.findIndexInSeBabylonianYearMonthPeriod([
+      seBabylonianYear,
+      mesopotamianMonth,
+    ])
+    return data.babylonianCjdnPeriod[i] + mesopotamianDay - 1
+  }
+
+  calculateYearOffset(currentMonth: number, offset: number): number {
+    return currentMonth + offset > 12 ? 1 : currentMonth + offset < 1 ? -1 : 0
+  }
+
+  calculateNewMonth(currentMonth: number, offset: number): number {
+    return ((currentMonth + offset + 11) % 12) + 1
+  }
+
+  updateBabylonDate(
+    cjdn: number = this.computeCjdnFromModernDate(
+      this.calendar.year,
+      this.calendar.month,
+      this.calendar.day
+    )
+  ): void {
+    const weekDay = this.computeWeekDay(cjdn)
+    const [
+      i,
+      lunationNabonassar,
+      seBabylonianYear,
+      mesopotamianMonth,
+    ] = this.computeBabylonianValues(cjdn)
+    const [j, regnalYear] = this.computeRegnalValues(seBabylonianYear)
+    this.updateCalendarProperties({
+      year: this.calendar.year,
+      month: this.calendar.month,
+      day: this.calendar.day,
+      cjdn,
+      weekDay,
+      lunationNabonassar,
+      seBabylonianYear,
+      mesopotamianMonth,
+      regnalYear,
+      i,
+      j,
+    })
+  }
+
+  private findIndexInSeBabylonianYearMonthPeriod(
+    yearMonth: [number, number]
+  ): number {
+    const i = data.seBabylonianYearMonthPeriod.findIndex((ym) =>
+      _.isEqual(ym, yearMonth)
+    )
+    if (i === -1)
+      throw new Error('Could not find matching Babylonian date in data.')
+    return i
+  }
+
+  private computeModernDateFromCjnd(cjdn: number): [number, number, number] {
+    const b = cjdn + 1524
+    const c = Math.floor((b - 122.1) / 365.25)
+    const d = Math.floor(365.25 * c)
+    const e = Math.floor((b - d) / 30.6001)
+    const day = b - d - Math.floor(30.6001 * e)
+    const month = e < 14 ? e - 1 : e - 13
+    const year = month > 2 ? c - 4716 : c - 4715
+    return [year, month, day]
+  }
+
+  private computeCjdnFromModernDate(
+    year: number,
+    month: number,
+    day: number
+  ): number {
+    return (
+      Math.floor(365.25 * (month < 3 ? year - 1 : year + 4716)) +
+      Math.floor(30.6001 * (month < 3 ? month + 12 : month + 1)) +
+      day -
+      1524
+    )
+  }
+
+  private computeWeekDay(cjdn: number): number {
+    return ((cjdn + 1) % 7) + 1
+  }
+
+  private computeBabylonianValues(
+    cjdn: number
+  ): [number, number, number, number] {
+    const i = data.babylonianCjdnPeriod.findIndex((cjdnPd) => cjdnPd > cjdn)
+    const [
+      seBabylonianYear,
+      mesopotamianMonth,
+    ] = data.seBabylonianYearMonthPeriod[i - 1]
+    return [i, 1498 + i, seBabylonianYear, mesopotamianMonth]
+  }
+
+  private computeRegnalValues(seBabylonianYear: number): [number, number] {
+    const j = data.rulerSeYears.findIndex((year) => year > seBabylonianYear)
+    return [j, seBabylonianYear - data.rulerSeYears[j - 1] + 1]
+  }
+
+  private updateCalendarProperties(props: CalendarUpdateProps): void {
+    const { cjdn, weekDay, year, month, day } = props
+    this.calendar.cjdn = cjdn
+    this.calendar.weekDay = weekDay
+    this.applyModernDate({ year, month, day })
+    this.applyBabylonianDate(props)
+    this.applySeleucidDate(props)
+  }
+
+  private applyBabylonianDate(props: CalendarUpdateProps): void {
+    const { cjdn, seBabylonianYear, mesopotamianMonth, i, j } = props
+    const mesopotamianDay = cjdn - data.babylonianCjdnPeriod[i - 1] + 1
+    const mesopotamianMonthLength =
+      data.babylonianCjdnPeriod[i] - data.babylonianCjdnPeriod[i - 1]
+    const ruler = seBabylonianYear < 161 ? data.rulerName[j - 1] : undefined
+    const regnalYear = seBabylonianYear - data.rulerSeYears[j - 1] + 1
+    const lunationNabonassar = 1498 + i
+    this.calendar = {
+      ...this.calendar,
+      mesopotamianDay,
+      mesopotamianMonthLength,
+      mesopotamianMonth,
+      ruler,
+      regnalYear,
+      lunationNabonassar,
+    }
+  }
+
+  private applySeleucidDate(props: CalendarUpdateProps): void {
+    const { seBabylonianYear, mesopotamianMonth } = props
+    const seMacedonianYear =
+      seBabylonianYear > 0 && mesopotamianMonth < 7
+        ? seBabylonianYear
+        : seBabylonianYear > -1 && mesopotamianMonth > 6
+        ? seBabylonianYear + 1
+        : undefined
+    const seArsacidYear =
+      seBabylonianYear >= 65 ? seBabylonianYear - 64 : undefined
+    this.calendar = {
+      ...this.calendar,
+      seBabylonianYear,
+      seMacedonianYear,
+      seArsacidYear,
+    }
+  }
+}