How does a tribe show that it lost its government-to-government relationship?

For a tribe to qualify as having lost its government-to-government relationship for purposes of § 292.7, it must show that its government-to-government relationship was terminated by one of the following means: (a) Legislative termination; (b) Consistent historical written documentation from the Federal Government effectively stating that it no longer recognized a government-to-government relationship with the tribe or its members or taking action to end the government-to-government relationship; or (c) Congressional restoration legislation that recognizes the existence of the previous government-to-government relationship.