Illustrations of history

I was surprised to see no fortifications as native american villages much smaller in my region had fortfications. I've just read the Wikipedia article and it says fortifications have been found.

Its population was huge:

Thus the population are also far larger than before thought with conservative estimations at 12,000, a probable average of 29,000 inhabitants but with the possibility of 46,000 inhabitants.

The Cucuteni–Trypillia culture:

The 'mega-sites' of the culture, which have been claimed to be early forms of cities, were the largest settlements in Eurasia, and possibly the world, dating to the 5th millennium BC.

The population of the culture at its peak may have reached or exceeded one million people.

Something I found odd too was the lack of fields in the illustration, though maybe they just are outside the frame. Of course, the Cucuteni-Trypillia people grew plants:

They cultivated club wheat, oats, rye, proso millet, barley and hemp, which were probably ground and baked as unleavened bread in clay ovens or on heated stones in the home. They also grew peas and beans, apricot, cherry plum and wine grapes – though there is no solid evidence that they actually made wine.