Alta River (Ukrainian: Альта, Ільтиця, Alta, Iltytsia) is a small river in Ukraine and is a right tributary of the Trubizh. The ancient town of Pereiaslav is situated between the Trubizh and Alta rivers.
The river is considered the place where the assassins sent by Sviatopolk the Accursed killed saints Boris and Gleb in 1015. In 1019 it was the site of a battle between Svyatopolk and his brother Yaroslav I the Wise which Yaroslav won.
Pereiaslav is a historical city in Boryspil Raion, Kyiv Oblast, central Ukraine. It is located near the confluence of the Alta and Trubizh rivers some 95 km (59.03 mi) southeast of the capital Kyiv. It was one of the key regional centers of power during the Middle Ages and served as the capital of a principality. Pereiaslav hosts the administration of Pereiaslav urban hromada, one of the hromadas of Ukraine. Its population is approximately 26,273 (2022 estimate).
Possessing more than 20 museums, Pereiaslav is often described as a "living museum", and was granted the status of Historical and Ethnographic Reserve.