[muawiyah]

The Sumerians might well be contemporaries, but the Mayans come along several thousand years later.

Iranian archaeologists recently reported finding an old settlement with writing that dates back older than anything the Sumerians did.

This dig in China is old but there's no writing.

[swarthyguy]

OK if not Mayan, then perhaps the mysterious Olmecs. Just a general impression.

And if the Pakistanis ever allowed the Indus River ruins to be properly investigated, who knows what we'd find there as well.

[blam]

Lost Civilization From 7,500BC Discovered Off Indian Coast

See post #18 in the above linked article. This may be writing.(?)