Simplify the following text for a Grade 9 native English-speaking person.
Original: Hulagu 's army greatly expanded the southwestern portion of the Mongol Empire , founding the Ilkhanate of Persia , a precursor to the eventual Safavid dynasty , and then the modern state of Iran .
Simplified: Hulagu 's army greatly expanded the southwestern portion of the Mongol Empire , founding the Ilkhanate of Persia .