Diplomatic action
"The Elves came to Khorvaire for a brief amount of time. However, events in Aerenal quickly forced them to return home. The Dhakaani, in an effort to make sure that they never returned, made a deal with the elves that they could only return to Khorvaire if invited, something the Dhakaani never planned to do. Although, the Elves would not forget this condition."
The History of the Elves by Professor Zeldyr of Morgrave University