But these Slavs did not settle in vacant areas, as has been contended; they came across an indigenous Greek population, who, due to attacks and upheavals, had gathered mainly in city centres. Slav settlers soon came into contact, with that Greek element, much superior culturally and politically, developed relations with them and were strongly influenced by them60.
Prudent and realistic policies by the Byzantine emperors also contributed decisively to the integration of Slav settlers into the Byzantine system, thereby assimilating and hellenising them. To this end, they used various means depending on the circumstances; military, whenever they had to put down a revolt or reinstate imperial authority or put under their control a rebellious Slavic group. Or frequently peaceful: administrative and ecclesiastic, demographic and economic. Sources mention military expeditions by Byzantine emperors against the Slavs in the Greek area, which started from the mid-7th c. Initially, these expeditions were carried out in Northern Greece and resulted in the gradual reestablishment of Byzantine authority.
Military operations, though, were not the only means of subjugating the new settlers. A basic policy of the Byzantine administration was a demographic measure, the forcible transfer of populations. By transferring Slavic populations to Asia Minor, the Byzantine empire achieved two things: on one hand the Slavic element in the Hellenic area was arithmetically weakened, and on the other hand assimilation was facilitated, since Slavs who were transferred to Asia Minor found themselves amidst a flourishing and numerous Greek population. But this demographic measure was even applied vice-versa, that is, Greek populations from Asia Minor were transplanted into Slavic populations ("epi tas Sklabinias") in order to reinforce the Greek element in these areas. Thus we learn, for example, that emperor Nicephorus (802-811) established in the northern Greek area populations which he transferred from all administrative districts ("ek pantos thematos") of Asia Minor61.
Furthermore a new adminstrative organization of themata (i.e. administrative districts with a general at the head) that was generally put into practice during this critical period, reinforced imperial rule and made control of Slavic groups more effective. Between 680 and 685 the "thema of Thrace" was established and in in 695 for the first time the "thema of Hellas" is mentioned. In the 9th c. reorganization was further reinforced by a division into smaller administrative units - a general tendency of the era: the "Thema of Macedonia" with Andrianople as capital (mentioned for the first time in 802); the "thema of Strymon" and the "thema of Thessaloniki" were established at that time.
We find out, therefore, that the Byzantine state followed a realistic and consistent policy in order to cope with the problem of Slav settlers, a policy that led to the control and integration of Slavic races by the empire. In this way the Byzantine state contributed decisively to their assimilation by the indigenous population and to their Hellenization.
The almost total lack of remnants of Slavic civilization (burial customs, dwellings, techniques and types of ceramics)62 testifies to this assimilation, which of course, could never have been achieved without the presence of an indigenous Greek population.
In the work of assimilation an essential role was also played by the Church, which had, by then, been reorganized and administratively reinforced in order that Slav settlers could be integrated into it. Thus, by the end of 7th c. at the VIth Synod (680/681) and at the Synod in Dome (692) five dioceses are mentioned in Macedonia: those of Thessaloniki, Philippi, Amphipolis, Edessa and Stobi. The number is significant, especially when compared to other areas of the empire, and it must be stressed that the seats of these dioceses are found at vital points in the area. Thus, the establishment of Amphipolis's diocese at the mouth if the Strymon was apparently aimed at reinforcing the Byzantine presence towards Strymonite Slavs and the reestablishment of Stobi's diocese in NW Macedonia, at supporting - in cooperation with the diocese of Edessa - the policy of Byzantium towards Slavs Drogoubites and maybe even at achieving their eventual Christianisation63.
The Christianising of Slavs in Hellenic territory took place gradually in different localities even before the official Christianising of the Slavic world outside the Byzantine Empire by Cyril and Methodius.
Regarding the work of Constantin-Cyril and Methodius, the two Thessalonian brothers, the whole argument of Skopje does not stand up to the slightest scrutiny. There is such an extensive bibliography64 about the two Apostles of the Slavs, their work and their ethnic origin, that any repetition is uprefluous. However I must emphasize that the two brothers were-eminent representatives of the Byzantine spirit, of the Greek and Christian civilization which had been reborn after the Iconoclast period65. They had an extraordinary Greek education and were polyglots. Undoubtedly, they expressed Byzantine policy and they were fully conscious that they were Greeks66. They had undertaken other missions to the Arabs and the Khazars too apart from that to the Slavic world. Nowadays, even foreign scientists of Slavic descent consider them to be Greek.67.
As for the language, on which the Slavic alphabet was based and in which the two brothers preached Christianity, it could certainly not be a "Macedonian" dialect, that is a Slavic dialect of Macedonia. It is noteworthy that the Bulgarians maintain that the two apostles taught the new religion in Bulgarian68. Apart from the fact that at that time Slavic "daughter" languages had not yet evolved far enough to form the basis for a new written language69, the basic fact that Cyril and Methodius worked in distant Moravia should be stressed. Experienced missionaries as they were, they could not have used a dialect foreign to the Moravians, but a language comprehensible to the people of Moravia otherwise they would not have been so well received, made soon an impact or had the success that they had in their work: they taught the new religion in the Old Slavic mother language, which at that time was common among all Slavs, and for this reason their work spread very rapidly throughout the Slavic world. The first translations of the Holy Scriptures and of legal texts etc. from Greek into the Slavic language were made in this Old Slavic mother language and not in "Macedonian" or another dialect.
To sum up, we observe that during the Middle Ages Slavs settled in Macedonia, as well as in other Greek regions, but they did not alter the ethnic physiognomy of the region. The "Tactics" of Leon VI the Wise, in the beginning of the 10th c., report characteristically: "My late father and emperor Basil had persuaded the Slavic tribes to change their ancient customs, and hellenised them, and subjected them following the roman system, liberated them from their leaders, honoured them by the baptism and trained them to fight against people at war with the Romans (= the Byzantines)"70. As Paul Lemerle writes, "Byzantium christianized, civilized and assimilated these Slavs, making them Greeks. And this is one of the most impressive victories of the Greek genius"71.
It should also be noted that at the time when the Medieval Serbian State was flourishing (mid-13th - mid-14th c.) and especially at the time of Stefan Dusan (1331-1354), the Serbs expanded their domination into Macedonia and in particular into Northern Greek territory. However, no source mentions that the conquered population was Slavic: the Serbian expansion is mentioned in contemporary sources, as a conquest of Greek regions. The Serbian domination was characterized as "illegal and tyrranical" and considered to be alian domination72.
It is also remarkable that a few years later, during the first siege of Thessaloniki by the Turks (1383-1387), King Manuel Palaeologus, in his speech "Admonition to the people of Thessaloniki", urges the inhabitants to fight to death, fot this is what their historical tradition decrees: "because we are Romans (= Byzantines, Greeks) and our country is the one of Philip and Alexander". This means that he, as well as the inhabitants, were conscious of the historical continuity of Hellenism and of their Greek origin which had its roots in ancient times73.