Why was the global footprint so much smaller in ancient times?

I am doing a project on Jesus and I need some background information. One of things I need to do is - "Estimate the Global footprint during the time of Jesus." I am thinking the footprint would have been smaller, but I only have 1 justification and that is that they didn't have vehicles, they used donkeys and camels (I think they used camels...?) for transport. Any suggestions would be much appreciated. Thanks everyone! xox