Thucydides gives only the duration (245 years) and the event that ended it (expulsion by Gelon). Both endpoints of the absolute placement are therefore inference, which is why circa is set and no competing reading is quoted — Jerome's Chronicon has no Megara Hyblaea entry in the on-disk capture.修昔底德只给出居留年数（245 年）与终结事件（革隆驱逐）。绝对定位的两端皆为推算，故标 circa；磁盘所见哲罗姆《编年史》无此城条目，因而不列异读。
The accounts记述 · the ancient witnesses
Greek historians · 希腊史家
Thucydides — History of the Peloponnesian War （修昔底德·伯罗奔尼撒战争史）primary source · 源典
§ 6
Thuc. 6.4.1–2 — Lamis' Megarians, after Trotilus and Thapsus, settle where the Sicel king Hyblon invited them; they live there 245 years until Gelon expels them修昔底德 6.4.1–2——拉米斯所率麦加拉人历特罗提洛斯、塔普索斯后，应西凯尔王许布隆之邀定居；居 245 年，至革隆将其逐出
Diodorus Siculus — Library of History （狄奥多罗斯·历史丛书）witness · 见证
Provenance: “primary source” = curated canonical witness (editorial); “dated witness” = derived from the ToposText date index by year-span, with the matched loci count. Sparse counts may include incidental mentions.出处：「源典」为校订之正典见证（编辑判断）；「系年见证」由 ToposText 系年索引按年代跨度推得，附匹配条目数；稀少者或含偶涉。
On the timeline时间轴上
→ See this and all 18 historians on the chronology spine于编年脊柱上一览本事件与全部 18 位史家