(CNN)The Navajo Nation, which spans parts of Arizona, New Mexico and Utah, has 34 communities with "uncontrolled spread" of Covid-19, its president's office said in a statement.
Navajo leaders say the spread is "largely due to travel off the Navajo Nation and family gatherings," according to the release.
A 56-hour curfew will start Friday at 9 p.m. to counter that, the statement said.
"We are dealing with an invisible monster and the only way we are going to beat this virus is by doing it together and listening to our public health experts," said Navajo Nation President Jonathan Nez in the statement.
The Navajo Nation was a prominent hot spot for Covid-19 in the United States earlier this year. In May, it surpassed New York and New Jersey for the highest per-capita infection rate.
Nez cited multi-generation living situations, a lack of running water, and fewer places to purchase food as causes for increased spread of the disease in May.
Residents in the impacted communities are "advised to stay on the Navajo Nation and refrain from off-Reservation travel," a public health order from the Navajo Department of Health said. "Individuals are also advised not to gather with anyone outside your immediate household and stay within your local communities."
There have been 12,720 confirmed cases in the Navajo Nation, its department of health website says, and 595 deaths. It has a population of 173,667, according to Census data.