Manasseh started out while he was still only twelve years of age, with the longest period of reign of all the kings of Judah and Israel. The fact that he started so young can be because his father, Hezekiah, had died, or he started at that young age as co-regent, being guided by his father (who knew in which year he was going to die, see 2 Kings 20:6). Because of the difficulties with the chronology, this is hard to verify. The name of Manasseh’s mother means: my (i.e., the Lord’s) pleasure rests on her.
1 Manasseh was twelve years old when he began to reign, and he reigned fifty-five years in Jerusalem. His mother’s name was Hephzibah.