Arsamosata (in Armenian Ashmushat or Shimshat) was a city of Armenia on the banks of the Euphrates River. It was founded by King Arsames I of the Orthodox dynasty. It was head of a military district from the 395. Persian possession until 591, year in which it was returned to the Roman Empire and in which, with its region, the Anzitene and the Astiatene, was created a new denominated province Armenia Fourth .

It fell to the Muslims and was besieged by the Byzantines in 837. By 960 it was once again Byzantine.

Ritter identifies her with Kharput, and D'Anville considers it to be Tigranocerta.

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