Who married Переяслава Даниловна?

Переяслава Даниловна (польск. Perejesławą; ум. 12 апреля 1283) — княжна из рода Рюриковичей, в браке княгиня-консорт Черска и Мазовии.

Siemowit I of Masovia (Polish: Siemowit (Ziemowit) I mazowiecki) (d. 23 June 1262), was a Polish prince member of the House of Piast, Duke of Czersk during 1247–1248, Duke of Masovia (except Dobrzyń) during 1248–1262, ruler over Sieradz during 1259–1260.

He was the sixth son of Konrad I of Masovia and his wife Agafia of Rus.