Don't discount "all" Lost Tribes. There's no objective reason, for instance, to reject the oral tradition of Kurdish and Bukharian Jews that they descend from the Lost Tribes. And there are several things that support such a tradition, including the fact that they inhabit the exact areas that the Lost Tribes were originally exiled to. It's quite reasonable to assume that, just as most Jews descend directly from Jews who returned from the Babylonian Exile (Ashkenazim and most Sephardim) or stayed in Babylon (Iraqi and Persian Jews) and correspondingly descend from the Southern Kingdom, that certain small isolated communities not connected to the Babylonian Exile (such as the Kurds and Bukharians) might descend in large part from the Northern Kingdom.
In my mind, the aliyah of these communities (who self identify as Lost Tribes and have maintained a continuous practice of Judaism for thousands of years) fully fulfilled the Biblical prophecy of a remnant of the Lost Tribes returning.
Then there are other communities, like the Samaritans. The Samaritans inhabit the area of the Northern Kingdom, practice ancient Hebrew religion, speak Hebrew and Aramaic, are genetically identical to Jews, and claim descent from the Northern Tribes. Plus Assyrian historical records support the Samaritans' claim that only the nobility and upper classes were exiled, not the common people. In fact, the only thing that disputes their claim are a few politically charged passages in Kings, Chronicles and the Talmud that claim they are Cutheans who converted out of fear of lions.
Once you accept these claims, accepting other partial claims is logical. We know, for example, that there used to be millions of Samaritans. While many were killed during various revolts, that can't explain the total drop in numbers (there are only 600 today). The best explanation is that many wound up converting to Christianity or Islam, and that their descendants mixed with the descendants of local Arabs (such as the Nabateans), Greeks, Romans, and later invaders (such as Arab, Turkish and Crusader) to become today's Palestinians. Similarly, population stagnation suggests that many Kurdish Jews over the centuries converted to Islam, becoming one of the ancestor groups for today's Kurds.
The language of the holy books is authoritative, politically charged or not.