Farming, simple irrigation systems, pottery and other crafts (with objects of great beauty made for the upper class), walled cities, some siege engines, long distance trade, domestication of animals, iron working, sailing, class divisions, chariots and writing.

This they could all eventually develop with no input from the outside in favourable climactic conditions.

Exposed to outside influence I think they can pick up things like clockwork, ocean worthy ships, machine tools, the internal combustion engine, radio and television (and improve it on their own as well). Even basic nuclear technology, computers and some complex medical equipment isn't completely out of the picture, though don't expect any refinements. As a society they can probably get clean water, electrification, good roads, decent hospitals, reasonable safety from crime and quality primary school education.

This is what I'd expect of a civilization with an average IQ of 70. But please remember this civilization requires some adaptation, what I wrote goes for a "civilized" people (or at least a people that practised farming for some time) with an IQ of 70. Not all hunter gatherer populations with that IQ would be able to make this work. Self-domestication in humans isn't really primarily about raising IQ as some people assume it is.