Complex sentence: One day Ryu's father had an encounter with Genma Saotome, after Genma found out about the Kumon's financial problems he gave Ryu's father a scroll containing the deadly secret art of Yama-senken aka Thousand Mountains.
Split into simpler sentences: One day Ryu's father had an encounter with Genma Saotome. After Genma found out about the Kumons' financial problems, he gave Ryu's father a scroll containing the deadly secret art of Yamasenken, a.k.a. Fist of One Thousand Mountains.