Upvote:0
There was the Indus, the Mesopotamian, the Yellow, and some might even say the Yangtze. Also, there is a debate whether the Nile civilization counts as an independent invention of civilization because people don't know for sure if they created the civilization themselves or if people from the Mesopotamian civilization migrated there as the Nile civilization appears to have formed a full 300 years after the one in Mesopotamia.(A long time to migrate south). Also, some as well consider the Mesoamerican civilization as being one of the early river valley civilizations.
--Overall, there might be 3 or 4 or 5. It all depends on which professor you ask.
Upvote:5
China actually had two separate ones: The Yellow river and the Yangtze. The Yellow river is likely the initial homeland of the Han people. However, the Yangtze is where the staple crop of rice was most likely domesticated. Eventually the Han expanded and overran the Yangtze basin as well, supplanting the locals. However, they kept their rice.
Other places that seemed to have developed native agriculture independently were the Olmec in the Coatzacoalcos River basin (staple - corn), the Caral in Peru in the Supe river valley (domesticated potatoes, Quinona, and a variant of cotton), and the New Guinea highlands (sugar cane for sure, not sure what else)*.
Wikipedia as always, has a list. However its not complete (no New Guinea), and there of course may be others that expired and have not been discovered yet.
* - Currently the oldest site found is at Kuk, on the Wahgi river valley, with evidence of sugarcane, taro, and banana cultivation. The irrigation works there date back 9000 years (!)