Why did trade groups such as the hanseatic league form

Merchant circles established the league to protect the guilds' economic interests and diplomatic privileges in their affiliated cities and countries, as well as along the trade routes which the merchants used. The Hanseatic cities had their own legal system and operated their own armies for mutual protection and aid.

this means that germany had to pay the allied countries. reparations are/is essentially payment for something that they have done wrong, so after ww1, germany was forced to pay reparations so they could replenish the allied countries resources' that they had lost during the war.