Complex sentence: Groups of the Cumans settled and mingled with the local population in regions of the Balkans, and Cuman settlers founded three successive Bulgarian dynasties (Asenids, Terterids, and Shishmanids) and the Wallachian dynasty (Basarabids).
Split into simpler sentences: Groups of the Cumans settled and mingled with the local population in regions of the Balkans. Those Cumans that settled in the Balkans were the founders of three successive Bulgarian dynasties (Asenids, Terterids, and Shishmanids) and the Wallachian dynasty (Basarabids).