Nomads are groups of humans who live by moving between locations. Intimate with their mounts, comfortable as warriors and travelers, nomads traverse some of the more arid regions of the world in roving bands. This is not always pleasant for those settled people the nomads encounter: for some nomads, the farms of settled people are there for the taking.
The intimacy that the nomads possess with nature allows them to practice effective camouflage tactics, and frequently gain surprise when trying for ambush.
Nomad bands travel with mounts, and are comfortable on horseback. They domesticate wild animals proficiently, and breed them for captivity. They favor their mounts in combat, attacking using bows, javelins, spears, and lances.
Ocean-going nomads make use of boats in a simlar way that other nomads make use of mounts.
Nomads equip themselves lightly, but well. Every nomad has a horse, and each has bows, javelins, spears, and lances to use while on horseback. A few might possess shields or swords or crossbows as well.
When they camp in an area, nomads make use of extensive tents, yurts, tipis, and wagons.
Large nomad groups are lead by fighters and theives of significantly high skill, spread fairly evenly throughout the hierarchy. The nomad leaders work together with skilled wizards and clerics of deities related to nature, travel, or ancestors (the clerics tend to be a bit weaker than the wizards or fighters in the force) as a matter of course -- few nomad groups are found without at least a few priests.
Nomads -- as you might expect -- don't build lairs of their own. They make encampments, sometimes for several months, especially in seasons when travel is difficult. They lair near bodies of water, and defend their camp with scounts and with bows and swords.