Simplify the following text for a Grade 8 native English-speaking person.
Original: Liu named his dynasty `` Han '' , historically known as `` Western Han Dynasty '' , and he became known as Emperor Gao ( or Gaozu ) .
Simplified: After defeating the great King , Xiang Yu , Emperor Gaozu of Han unified China and became the first emperor of Han Dynasty . Emperor Weidi of Han , Gaozu 's son , was the 2nd emperor of Han Dynasty .