Interesting, and plausible, but if their ancestors have been Jews for thousands of years, why do they need to be “converted”?
http://www.moshiach.com/features/tribes/burma.php
...According to the history which they state, they were exiled to Assyria in 722 BCE with other Tribes of Israel. Later, Assyria was conquered by Babylon (607 BCE), which later was conquered by Persia (457 BCE), which later was conquered by Greece of Alexander the Great (331 BCE), when the people of Menashe were deported from Persia to Afghanistan and other places.
There they became shepherds and idol worshipers. With the conquest of Islam, they were forced to convert to Islam. Because they speaking Hebrew they were called the Semitic speakers...
...From Afghanistan their migration continued eastward until they reached the area of the Tibetan-Chinese border. From there they continued into China following the Wei River until they reach the central China. They settled there at about 231 BCE.
But the Chinese were cruel to them and enslaved them. Some of them escaped and lived in caves in the mountainous areas called Shinlung, which became another name for the tribe of Menashe. They are also called the cave people or the mountain people...
Later they were banished from their cave area and went west through Thailand and eventually reached the area in Myanmar.
There they wandered along the river until they reached Mandaley. From there they reached the Chin Mountains. In the 18th century a part of them migrated to Manipur and Mizoram which are in northeastern India. Generally, they maintained the tradition about their wandering and they realized that they were not Chinese even though they spoke the local language.
They call them themselves Lusi which means the Ten Tribe (”Lu” means tribes, and “si” means ten)...
...In 1854 with the arrival of the first American missionary, V. Petigrore of the Baptist Mission, the church was established. In 1910 more missionaries came and they established churches in their area of northern India. As a result, the tribal priest lost his stature and the community was subjected to Christian influences and pressure. With the spread of Christianity along the land, they were again subject to great pressures and many of their religious articles were then thrown away or burned by the British and American missionaries between 1854-1910.
Recently a return to Judaism began. Several thousand people of Menashe decided to observe the laws of the Torah and returned to Judaism. They have synagogues in Manipur, Assam, and Mizoram. There are also those who emigrated to Israel. Thousands long for returning to Israel...