To what end? What is the goal? Amassing gold? What is that going to get them other than better gear? They need incentive. Big groups get towns, castles, villages, titles, all kinds of notable stuff.
Ask them, madmanjack, gimest de gyrst, tybalt, boerenlater, lemon, elkska, brigadier and so on - more coming and asking if they can help out - no promises of gold, no nothing. We promise to give what they need if we can in terms of resources. And we will later today transfer the village of Ushkuru, so they can trade freely there and have a safe haven. Torben, will be the one managing it and it will be under the protection of us.
Incentive? Differs I guess, teamplay, ability to kick some big clannuts when these guys work together, back up from a clan, possibility to get info about traders they can raid and so on.