Simplify the following text for a Grade 11 native English-speaking person.
Original: Seleucus I Nicator won the territory of Syria , and he founded four `` sister cities '' in northwestern Syria - Antioch , Seleucia Pieria , Apamea and Laodicea-on-the-Sea .
Simplified: Seleucus I Nicator won the territory of Syria , and he proceeded to found four `` sister cities '' in northwestern Syria , one of which was Antioch .