Tony’s father comes from a line of nomadic cowboys who ranged over the llano, the plains, never staying too long in any one place...
Tony's father, Gabriel, is a Marez. The land is wide open and inviting for the Marez line. They take their name from the sea and discuss several times in the novel the idea that the freedom and expansiveness of the sea remains in their blood; part of their character.
“These were the people of my father, the vaqueros of the llano. They were an exuberant, restless people, wandering across the ocean of the plain.”
The llano, for Gabriel, continues to call to him. He repeatedly expresses his desire to move to California - not because he knows what is out there, but because he doesn't. He craves the freedom of movement. Freedom, adventure and fulfillment are all nearly synonymous for the Marez.
Though Gabriel ultimately decides that he no longer wants to wander, but instead prefers to make sacrifices to keep the family together, the llano is thoroughly associated with the Marez character and inherited nature, which is one that craves open spaces and movement.