KENTARO12100
I think building city, sewers etc is too fast. For Max it would be better to show them with his small inventions that, IF they follow his ideas, they could live easily. For example, building javelin throwers or another kind of weapon would help them to fight with vikings. Or better alcohol or with this 21cc cooking ability, he could cook them something delicious etc. So that not just his family or small part of the tribe but whole 1500 would see him as their saviours and could build city.