Leland's Group is a group which appears in Season 4 of Fear the Walking Dead.
It can be assumed that before the apocalypse, the 'gang' only existed as a group of individual people who did not know each other but who lived in or around the Texas area.
It can be assumed that over an unknown length of time after the outbreak, the members of the group found each other and banded together under the leadership of Leland in order to survive. They seemed to have settled in the Trailer Park where they would ambush and rob other survivors. Eventually, they ambushed and tried to rob Morgan Jones, John Dorie and Althea but were largely overpowered.