BYZANTIUM AND THE SLAVS	341
The lists of Bishops from the Balkans attending the great
Councils grow steadily smaller from the middle of the sixth
century till by Heraclius's later days scarcely any inland city
except Adrianople and Philippopolis seems to have main-
tained its church. The bulk of the peninsula belonged to
the ecclesiastical province of Illyricum, a province as yet
under the bishopric of Rome. Heraclius therefore sent to
Rome for missionaries to re-establish Balkan Christianity.
This was probably a mistake. To the barbarian in the Balkans
Constantinople represented the glamour and majesty of
imperial civilization. Rome to them was not a reverend city
in Italy but an idea personified by Constantinople. Priests
from Rome lacked the prestige that priests would have who
came from the eastern capital. Moreover the Popes of the
seventh century were no great missionaries and had anxieties
nearer home to distract them, while the imperial Government,
face to face now with the terrible menace of the Saracens,
troubled itself no more about its Balkan vassals. The
missions faded away; and the only Slavs to become Christian
were those whose lives brought them into contact with the
Christian cities of the coast. Amongst the Slavs round
Salonica St. Demetrius began to be paid a proper reverence;
but that was almost all.
The opportunity was missed. It was left to another race
to organize the Balkan Slavs, and to lead them against the
Empire. The Bulgars were a nation of Hunnic origin who
on the decline of the Empire of the Avars established them-
selves on the northern shores of the Black Sea. After
Heraclius's intervention the peninsula seems to have enjoyed
a rare interval of tranquillity; but in 679^ when attacks from
the Chazars had broken up the short-lived kingdom known
later as Old Great Bulgaria, a large section of the Bulgars
crossed the Danube under their Khan Asperuch and settled
in the Delta and the Dobrudja. The Emperor Constantine
IV set out to defend the frontier, but an attack of gout
brought him home from the war. His leaderless army was
forced to retire; the Bulgars followed, and in the course of
the year 680 established themselves between the river, the
Black Sea, and the Balkan range, roughly from Varna for a
hundred miles to the west. The Emperor Constantine made