It’s a land leased property typically a long term lease. Be careful with these as the ones in AZ have been emptied out and taken over by the tribe when the lease ended. There was a whole bunch of lawsuits by tenants against the owners due to not getting enough notice.
Typically these land leased parks start emptying out once you hit the 10 year mark on the land lease. Land lease also makes it difficult to make any improvements, investors are often forced to be slumlords since improving the property is often a money loser when the lease has a limited time left on it.
On the reservation here in NC you have to be Native American to own land. They do land leases up to 99 years depending on the property. Not sure how it is out west, but here they have their own police dept, court system, and the chief/tribal counsel ultimately make the laws. Generally it is in your best interest to find a tribal member to be a partner in most business ventures on tribal land.
There are several parks on native land in southern Ca that have massive deffered maintenance and have been all over the news in the last year or so. One has a failing water system with arsenic over the maximum level. The unwillingness to invested could be related to ownership issues, or just running it into the ground.