Complex sentence: This left Miyoshi Yoshitsugu the adopted heir when Chokei died in 1564, too young to rule three men shared his guardianship-Miyoshi Nagayuki, Miyoshi Masayasu, and Iwanari Tomomichi.
Split into simpler sentences: This left Miyoshi Yoshitsugu the adopted heir when Chokei died in 1564, too young to rule. Three men shared his guardianship-Miyoshi Nagayuki, Miyoshi Masayasu, and Iwanari Tomomichi.