Quote from: walkerpTwo things I had not known.  Very cool. Thanks.

Take a look at the course of the lower Mississippi sometime. It loops like crazy, meanders into different courses - you'll see bits of one state on the wrong side of the river because the river changed course, splits into oxbows, and generally squirms like a snake. It's trying to drain into the Atchefalaya now, and only a massive dam and the constant efforts of the Corps of Engineers keeps it in its current bed at all.

As for farms, it makes sense. Cities are consumers of food, not producers. That doesn't mean the farmland has to be right next to it, of course - if the city site is important for trade reasons, those farms can be far away by sea. Rome imported its grain from Sicily, North Africa, and even the Black Sea, for example. Still, that food has to come from somewhere.

-clash

You know, I think dwelling too long on geography can take some of the fun about it.  When I do a map, I try to remember the basics, but I also am less concerned with every last geographical detail than with something that "looks right" to the human brain.  That means a reasonably accurate world design, no huge errors, but not worrying and redrawing everything 74 times along the way.  One of the best things to do for fantays maps and the like is to look at this map collection.  After a while, I think you sort of get a "flow" and general idea in your head for want you want your map to look like.

Obviously, if you want to be the next Pete Fenlon, then you'll have to take it from there.  But getting in the ballpark is as much of a step as some folks will ever need or want.

There are countless of examples were rivers flow "uphill". Of course the actual riverbed is always a slope, but a river can totally cut through hills & mountains.
There are several expalanations, but I don´t think anybody here is interested.

http://www.io.com/~sjohn/demog.htm is a website with some simple and easily usable information on population density, arable land size and the like in the middle ages. I guess some of it is relevant to this thread.