Complex sentence: They are first among all the Naga tribes to embrace Christianity and by virtue of this development the Aos avail themselves to Western education that came along with Christianity which led to Aos to become the pioneering tribe among the Nagas in many fields.
Split into simpler sentences: They are first among all the Naga tribes to embrace Christianity and by virtue of this development the Aos avail themselves to Western education that came along with Christianity. In the process the Aos became the pioneering tribe among the Nagas in many fields.