Below the passes of the Balkan range the plain of northern Thrace, from the valley of the Rose (Kazanlak) and Beroe (Stara Zagora) to the Tundzha at Diampolis (Yambol) and the hills behind Aetos (Aytos), has been the war zone between the Asen state and the empire since 1186.
Kaloyan raided Thrace often after his accession in 1197, and in the spring and autumn of 1199 Cumans and Vlachs from north of the Danube broke into the empire, probably without his leave (Madgearu). No truce is in force on 1 January 1200: the passes are Bulgarian, the walled towns of the plain and the Maritsa line are imperial, and the open country between is plundered from the north. Whether imperial garrisons still hold Beroe and Diampolis that winter is not pinned.
The next great raid is Kaloyan's of March 1201 (Constantia destroyed, Varna taken).
How things stand that morning
Raided, with no truce; neither side can farm the open plain in safety.
Who raids here
Kaloyan's Bulgarians and Vlachs; Cuman bands from beyond the Danube, sometimes on their own account.
Raided
The emperor's lands of northern Thrace (con).
Anchoring castles
Bulgarian side: Tarnovo and the passes of Tryavna, Shipka, Kotel and Sliven. Imperial side: Constantia (Simeonovgrad) and Adrianople on the Maritsa, Anchialos and Mesembria on the coast (con); Beroe and Diampolis not pinned.
Last campaign
Autumn 1199 (Cuman and Vlach raid, Madgearu); before it the raid round St George's day (23 April) 1199 that reached Rhaidestos and the walls of Tzouroulos (Thrace record, after Choniates); Kaloyan's own raids in 1197-1198.
What the year holds
What happened next, if nothing in play changes it. Each event carries what it depends on and what would stop it.
- March 1201Kaloyan and the Cumans destroy Constantia and take Varna.Depends on: No peace before then. Stopped by: A truce in 1200.
- Late 1201 or 1202Peace between Kaloyan and Alexios III closes the belt for a time.Depends on: Exhaustion after 1201. Stopped by: Continued war.
Where the sources disagree
Evidence: The raids of 1199 and the absence of a truce are well attested; the exact reach of the raids and the holders of Beroe and Diampolis are not. The Thrace researcher (con) may draw the same belt from the Byzantine side.
Sources and studies
- Kaloyan of Bulgaria (English Wikipedia), citing Madgearu, The Asanids (2016), Fine, The Late Medieval Balkans (1994), Curta, Southeastern Europe in the Middle Ages (2006), Stephenson, Byzantium's Balkan Frontier (2000)
- Kalojan (Zar) (German Wikipedia): Varna taken 24 March 1201; peace of 1201 or early 1202
- Second Bulgarian Empire (English Wikipedia)
Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.