“Jita is close to geographical center of New Eden and Caldari starting systems, had a level 4 agent and proximity to several region made cross-regional price-check easier.”

In the beginning yulai was the main market system, as it had express gates to each of the four factions. Jita was a mission running hub, with SEVERAL level four agents dispersed throughout the system. This meant that mission runners were selling large amounts of t1 and named modules. When the yulai gates were destroyed by “terrorists” making it much more difficult to get to, players found that there was already a large market present in Jita due to the mission runners. More and more players started selling stuff there until it became the Jita that we know now. At some point, CCP removed many of the agents in Jita and put them in different places. (Rens, Hek, most of the secondary market hubs) But Jita stayed the predominant market hub in New Eden.