(NewsNation) — Even as Arizona tries to find ways to fill in gaps along the border wall in the Yuma sector, there is a mile-long area that remains open because it runs into sovereign tribal land.

Arizona Gov. Doug Ducey issued an executive order one week ago to use money from the state’s border security fund to use shipping containers to fill five gaps in the wall.

However, a gap that has not been filled is one along the Cocopah Indian Tribe’s Reservation.

Hundreds of migrants have crossed into the U.S. through this hole. Border Patrol agents said they saw around 600 people go through it on Thursday.

The reason this particular gap exists is because of litigation that happened during the administration of former President Donald Trump.

When the Trump administration first started building a wall along the border, Arizona Public Media reported in June 2020, the plan initially included a barrier along the Cocopah Reservation’s 7-mile stretch of borderland east of the Colorado River. However, after lawsuits were brought by the Sierra Club and other parties, Trump administration attorneys removed funding for the Cocopah section of the wall.

Although Trump’s administration claimed the decision was based of difficult terrain and high building costs, other wall sections around the area would have cost the same, if not more, Arizona Public Media pointed out.

U.S. Rep Raúl Grijalva, a Democrat, told the news outlet at the time that tribal sovereignty was the real reasoning behind the decision.

“It would be foolish of Homeland Security of this administration to challenge sovereignty, because you’re challenging sovereignty at all levels if you do that,” he said at the time. “(That is) a project they can’t win.”

Cocophah tribal lawyers in 2020 sent a letter to Customs and Border Patrol saying that the tribe had been “kept out of the loop” about construction plans on the sovereign area, and that the area is the “cultural and spiritual heart” of their homeland. Building the wall, the lawyers said, would cut off the tribe’s access to the Colorado River, and to members living on the other side.

To this day, the gap in that area remains.

Border Patrol agents told NewsNation’s Ali Bradley it will act as a funnel, allowing them to work more efficiently because the migrants will be in one place.

Yuma has seen a 245% increase in encounters over last year, according to Customs and Border protection. They come from Ukraine, Russia, India, and Peru, although recently, the majority have been from Cuba.

One Cuban migrant, Ernesto, told Bradley he left Havana last month, then went to Nicaragua before traveling to Honduras, then Guatemala, then Belize, before coming to Mexico. He’s been traveling for 28 days.

To make the trek to America, he sold his house, and spent almost all his money.

“I am hoping really that this country opens its arms to me,” Ernesto said. “Because it’s not easy … the idea of going back. It’s not easy at all.”