Conditions to force nomadism?

[Alvary]

hey everyone!

Last few days I have been down with a cold so head just isn't working well for puzzling over gimp, so I have been thinking over different ideas for races of people; their behaviors / traditions and why they have them. There is an idea for a people I would love to use one day, but there is something I am stuck on...I would like to have something that dictates where they are during the year, something that forces them to be nomadic. Maybe they gather and shelter in cycles? The idea of a situation that has tides over a very large area, exposing rock pools for foraging fits the feel, but the time frame is too short.
So, if anything comes to mind that i could research or such, that would be fantastic! I'm afraid my stuffy head is failing me on ideas

Thanks for your time, back to lurking for me.
Alvary

[Steel General]

There could be any number of things...weather, follow herd animals, invasion by other peoples/creatures.

Just a few ideas quickly off the top of my head.

[Gandwarf]

A lot of people were nomadic because they were forced by the scarcity of natural resources. If they have their own herds overgrazing might be an issue... or if they hunt, they could follow their prey around.

You could also have rivers flooding, disease in some areas, bands of raiders appearing at specific times (maybe the raiders are farmers and during the winter they have free time ).

[Gidde]

It might be helpful to think of it in the opposite way ... humans started out nomadic and were only able to settle down when they were able to do serious agriculture. So take away their ability to farm (for any of the reasons mentioned above or others) and voila, you have nomads.

It could even be a religious observance of some sort ... against the precepts to plant anything, to exploit nature with agriculture, to live in permanent buildings, etc. etc.

[Greason Wolfe]

One other possibility, touched on in part by SG, would be extreme seasonal changes in the climate or a particularly long climate cycle (i.e. the whole Ice Trucker thing that aired on television where they can only run their trucks during the coldest part of winter). But Gidde hit the nail on the head, so to speak. Human cultures didn't "settle" down until after a certain level of agricultural advancement and, in many instance, the ability to handle herd animals.

GW

[Midgardsormr]

Even some agriculture-based societies are nomadic or semi-nomadic. There are tribes in South America that practice swidden agriculture (slash-and-burn) and are forced to regularly relocate because they wear out the soil. They usually move in cycles, returning to their old fields after several years once they've had time to regenerate.

[Meridius]

Transhumance is something you might want to google up. It isn't strictly nomadism, as people are only moving between two or more fixed points, but it might be interesting.

Other options include fragile land. In dry places where little rain falls vegetation is slow to recover (if at all). Like Midgardsormr described.

Another variant is early domestication, where domesticated animals ARE present but advanced agriculture isn't.

The exile of an entire group of people (or even a complete society) could be a very dramatic option.

Also already touched upon, conscious choice. People don't WANT to affix themselves to a permanent place, so they stay on the move.

About your example, that IS possible. I live in an area which is famous for man-made hills, where people lived on ('terpen', or in English something like: 'terps'). Before those hills where present, people probably DID migrate into this area. Remember, land sometimes only floods on stormtide, and not (or at least not completely) during regular high tide, or even the entire summer.

The reason should also depend on the general area the people you mentioned should live in. A jungle has different reasons for migration than a tidal marsh. And a desert has yet another set of possible options. There IS some overlap though.

[Ascension]

I was going to say something along the lines of what Gidde said - some great prophet had to move around for some reason and his followers continue the practice or simply because their god (via proxy of the clergy) tells them where to go and when. That could be pretty cool for a race of big, evil, and mean dudes rampaging around a continent in decade long cycles. Kind of weak for a pastoral culture who just follow herds or scrounge for food...that would make them a small culture whereas the aforementioned one could be dominating. The smallish culture would almost require some sort of ancient mysticism to make them interesting.

[Juggernaut1981]

Mimic the classic nomadic cultures: Bedoins & American Indians

Bedions
They live in a desert. There are highly limited resources everywhere and you need to move around to ensure you are in a reasonable climate (i.e. avoiding the blisteringly hard heat).

Nomadic American Indians
Following a primary food source, such as buffalo, around.

Nomads tend NOT to live near coastlines because those regions generally tend to have good water, good vegetation and good hunting for edible prey (fish, birds, mammals). This becomes more of the case as you head to the tropical regions because the weather allows you to not move to avoid cold/heat.

[Alvary]

Thanks for all the replies everyone. Most crossed my mind at some point, just not fitting too well...the ice truckers mention has sparked some ideas, I might go and see what I can find out about human movements that do or have in the past relied on ice. And marsh tides sound interesting...really need to do more looking into all things wet and boggy.
Haha Ascension that's an awesome idea. Sort of like land pirates.

Again, thanks all, off to do some reading up!
Alvary