The question asks to identify the name of the principality whose territory is hatched on the map.

The hatched area on the map corresponds to the territory of the ancient Russian principality of Chernigov. This can be determined by its geographical location relative to other named rivers and cities on the map, such as the Dnieper River and the city of Chernigov, which is typically located in this region. The hatching is a common cartographic method to denote a specific historical or administrative region.