In another incursion they [the Avars] placed under their control all of Thessaly and Greece, Old Epirus, Attica, and Euboia. They attacked and forcibly subjugated the Peloponnesus, expelling and destroying the noble and Hellenic peoples, and they themselves settled there. Those Greeks who were able to flee from the blood-stained hands of the Avars scattered themselves in various places: the inhabitants of the city of Patras resettled in the area of Rhegium Calabria, the Argives on that island called Orobe, and the Corinthians came to dwell on the island named Aegina. At this same time some of the Lakones, abandoning their ancestral homeland, sailed off to the island of Siciliy, and even today they are still in an area of Sicily called Demena, calling themselves Demenitai instead of Lacedaemonians but preserving their own Laconian dialect. Others discovered an inaccessible region [in the Peloponnesus] on the coast, and founded a strong city there--naming it Monemvasia because there was only one entrance to it--and they settled there with their own bishop. Their herdsmen and farmers settled in rugged areas in the vicinity and have recently been called Tzaconians. Thus the Avars, after they had conquered the Peloponnesus and settled there, held it for 218 years, that is from the year [587 A.D.], after the creation of the world 6096 the sixth year of the reign of Maurice, until 6313 [805 A.D.] which was the fourth year of the reign of the elder Nicephorus, whose son was Stauracius.
 
They were under the control of neither the Roman emperor nor anyone else. Only the eastern portion of the Peloponnesus, from Corinth to Malea, remained free from the Slavic nation on account of the rugged and inaccessible terrain in these areas. The Roman emperor used to appoint a "strategos of the Peloponnesus" over this region. One of these strategoi, a member of the Scleros family from Lesser Armenia, attacked the Slavic tribes, defeated and utterly destroyed them, and enabled the ancient inhabitants to recover their possessions. When he heard about this, the above-mentioned Emperor Nicephorus became filled with joy and desired to restore the cities there, to rebuild the churches which the barbarians had destroyed, and to convert these barbarians to Christianity. Wherefore, having made inquiry concerning the colony in which the former inhabitants of Patras dwelled, he ordered that they be resettled, along with their own bishop (who at that time was named Athanasius) on their former lands. He also granted to Patras the privileges of a metropolitanate; previously it had enjoyed the status of an archbishopric. And he rebuilt their city and the holy churches of God from the ground up, while Tarasius was still patriarch.
 

from Deno John Geanakoplos, Byzantium. Church, Society, and Civilization Seen Through Contemporary Eyes. Chicago/London, 1984, pp. 274-275.