"It also holds massive significance for the people of Te Rarawa, Te Tai Tokerau and the Far North.
"The return of the carving is recognition of the bond this taonga forges between the museum as its custodian, the people of Te Rarawa, its spiritual guardians and Te Ahu."
Te Runanga o Te Rarawa chairman Haami Piripi said last time the taonga was lent to Te Rarawa, for just one week, it had a striking effect on the iwi's spirit and morale.
This extended loan would make a major contribution to empowering iwi, "an essential element for the community development of our whanau and hapu".
Then museum chairman Phil Cross agreed.
"It was an incredibly emotive, positive experience, and one that created a real sense of pride," he said.
"It is indicative of the ethos that unless you know where you've come from, you don't know where you are going. The carving provides that sense of where things have come from."
The carving, which is said to show how Maori art evolved from its Polynesian origins, has a central figure with outward-facing manaia motifs at each end, like later door lintels. Tangonge is unique, however, in that both sides are fully carved, suggesting it may have stood over a gateway.