You can search for an Indigenous American treaty by tribe in the U.S. Statutes at Large database two different ways.
Begin by clicking on Advanced Search at the top of the main page. You will use the Tribe option from the drop-down menu for this search.
You can also search using the Just search for option from HeinOnline’s one-box search within the database to search the full text of the resources within. From here you would type tribe:Mahas and hit the search button.