Complex sentence: Kartavirya then defeated the Nāga, after which he made Mahishmati in present day Maheshwar capital of his kingdom, and prevented Ikshvaku King Bahu, descendant of Harishchandra, from taking back Ayodhya, which was his by birthright.
Split into simpler sentences: Kartavirya then defeated the Nāga, after which he made Mahishmati in present day Maheshwar capital of his kingdom. Kartavirya also prevented Ikshvaku King Bahu, descendant of Harishchandra, from taking back Ayodhya, which Bahu felt was his by birthright.