I thought the non-forested stuff was farmland - it seems to be split up in roughly rectangular chunks, and those little bits of green separating the chunks could be windbreaks. It seems like a ton of land though, don’t know how much farmland a Roman city like this would have (or if would be right outside it like that, I think the Romans did a lot of farming in villas some distance away from cities).

I think so, yeah. Romans were real big into chariots, they even had sponsorships and stuff, and racers could apparently make a ton of money. In the Eastern Roman empire it also ended up having a political aspect, and people would start riots over the wrong team winning.