Simplify the following text for a Grade 9 native English-speaking person.
Original: After Khomeini gained power , skirmishes between Iraq and revolutionary Iran occurred for ten months over the sovereignty of the disputed Shatt al-Arab waterway , which divides the two countries .
Simplified: After Khomeini gained power , small battles between Iraq and revolutionary Iran happened for ten months . They were fought over who controlled the the disputed Shatt al-Arab waterway , which divides the two countries .