Orientalis

Tachkastan aka to the South between the Roman Province of Mesopotamia and Syria. It is mentioned in the Pilgrimage of Egeria.

"...that place of the Chaldees where Terah lived at first with his family,*.... at the tenth station hence, as you go into Persia. There are five stations from here to Nisibis, and five stations thence to Hur,** which was a city of the Chaldees, but there is now no access for Romans, for the Persians hold the whole country.*** This district is specially called Orientalis; it is on the borders of the Romans, the Persians and the Chaldees."

1. *Gen. xi. 28.
2. **Ur of the Chaldees. Gen. xi. 28.
3. ***The Emperor Jovian had been forced to sign a treaty and surrender Nisibis and the district to Sapor in A.D. 363.