Complex sentence: The modern martial art of Hwa Rang Do was founded by two Korean brothers, Joo Bang Lee and Joo Sang Lee, who started their martial art training with their father who taught them Yudo and Kumdo at a young age.
Split into simpler sentences: The modern martial art of Hwa Rang Do was founded by two brothers, Joo Bang Lee and Joo Sang Lee. The Lee brother's martial art training started with their father who taught them Yudo and Kumdo at a young age.