Ships can't tack against the wind so, in a unobliging breeze, they have to be rowed. Also, windmills have not been invented nor any gear mechanism. The spinning wheel is still a century away and in some places there are no wheels at all. There are no universities, although there are some libraries. To use them scholars need to know Greek, Latin, Arabic or perhaps Chinese.
Scholarly life is short, though, because there are no eyeglasses.
Christianity, Buddhism and the Islamic faith are still religions of the cities. In the countryside, they are only a veneer over pagan beliefs. In some places any version of monotheism is a hard sell. It is tempting to think that thirty-three generations later nothing remains of these people who, like us, welcomed a new millennium. We play basketball, a version of which was played in Chichen Itza in the year 1000.