While Serbia was listening to the Turkish cavalry, the Ban of Bosnia,
Tvertko, raised that province to its greatest eminence. Being a
collateral heir of the old house of Nemania, and having wide Serbian
lands under his rule, he had himself proclaimed king on the tomb of
St. Sava in 1377. He called his banat "the kingdom of Serbia," and
allied himself to Prince Lazar, the most powerful of the Serbian
rulers who were still independent. In Bosnia at this time the Bogomile
heresy, after winning the people of Herzegovina, that wild and
mournful province, attracted not only the peasants but the bans. Just
as Du[vs]an and other Balkan princes had made of an autocephalous
Church the surest foundation of their States, so did the Bans of
Bosnia, beginning with Kulin at the close of the twelfth century, see
in the Bogomile movement a national Church that would render their
subjects more intractable to outside influences, to religious
suggestions emanating from Rome, and to political ambitions that came
from Hungary. The people, for their part, flocked to the ranks of the
"good Christians," as the sect was called, on account of the Bogomile
humility, the democratic organization of a Church that was in such
contrast with the formalism of Byzantine ceremonial, and also on
account of some pagan superstitions that were mingled with this
Christianity and made to these simple, recently converted Christians a
most potent appeal. It was in vain that the Popes preached a crusade
against the Bogomiles, in vain that the Kings of Hungary descended on
their heretical vassals; for the ban, in one way or another, would
divert that wrath--sometimes, if no other choice presented itself, he
became the temporary instrument of this wrath while standing at the
people's back. From all the world, so say contemporary records, there
was a constant stream of heretics to Bosnia, where now the Bogomiles
were found in the most exalted positions. Ceaselessly the Popes
persecuted them, and when at last in Sigismund of Hungary an ardent
extirpator visited the land there came about a terrible result, which
has made Bosnia so different from other Serbian territories.