[The following is an excerpt from P. Stephenson, Byzantium's Balkans Frontier:A Political Study of the Northern Balkans, 900-1204 (Cambridge University Press, 2000), ch. 1.]
Byzantine relations with Bulgaria were complicated in the early years of the tenth century: more complicated than many historians have allowed. The Bulgarian Tsar Symeon (c. 894-927) has been portrayed by both Byzantine and modern authors as an aggressor intent on capturing Constantinople from which he might rule a united Byzantine-Bulgarian empire. However, recent scholarship (notably the work of Bozhilov and Shepard) has questioned this, and maintained that Symeon's ambitions were more limited until the final years of his reign, the 920s, when he engineered a series of confrontations with the Byzantine Emperor Romanos I Lekapenos (920-44). (We will cover these years elsewhere: see the letters of Nicholas Mystikos and Theodore Daphnopates.) Symeon's died on 27 May 927, and his successor Peter (d. 967) immediately launched a major invasion of the Byzantine administrative district of Macedonia. As one of four sons such a show of strength would have been necessary to secure the support of his father's boyars. However, the Bulgarian troops withdrew swiftly, at the same time razing the fortresses that they had held until then in Thrace, and this early performance was not repeated. Instead, it heralded forty years of apparent harmony and cooperation between the two major powers in the northern Balkans. The reason for the withdrawal, and the centrepiece of the enduring Bulgarian Byzantine accord was the marriage in 927 of Peter to Maria Lecapena, granddaughter of the (senior) ruling emperor Romanus I Lecapenus.Peter has generally been held to have presided over the dramatic decline of Bulgaria. Thus Browning (1975: 194-5) concludes his stimulating comparative study with the observation 'the grandiose dreams of ... Symeon ended in the dreary reality of Peter's long reign, when Bulgaria became a harmless Byzantine protectorate'. Such interpretations focus on Bulgaria's military prowess, comparing Symeon's successes with his son's inactivity, and draw heavily on Byzantine narrative sources. If we examine the material evidence the indications are entirely different, suggesting a period of political consolidation and economic expansion. Byzantine sources, as much by their silences as their occasional references to the tsar's irenic disposition, bear testimony to the relative peace, if not the prosperity of Peter's reign and his good relations with Constantinople. This is not to suggest that Bulgaria was not considered a potential threat in Constantinople, for as we will see shortly many other peoples were considered suitable allies against Peter. Nevertheless, in the mid-tenth century the productive hinterland of Constantinople was no longer trampled under the boots of Bulgarian troops. Perhaps the most significant indication of the new status quo is the absence of any substantive chapter on the Bulgarians in the treatise known as the De Administrando Imperio (DAI). Compiled on the instruction of Constantine VII Porphyrogenitus, to whom it is generally attributed, it comprises 53 chapters of advice addressed to his son and heir Romanus II (959-63). Some chapters are culled directly from earlier histories to provide antiquarian information on peoples and places of contemporary concern to the imperial court. However, the chapters of greatest interest are those based on dossiers of information on the empire's neighbours compiled in the century before the work was completed c. 954. Virtually all that we know of Byzantine diplomatic procedure is based on the DAI, and it is possible to construct a detailed picture of imperial policy in the Balkans and beyond from a close examination of the text.
Two brief excerpts are available: