Plovdiv city was possibly at times a vassal of Bulgaria or Venice. Ivan Asen II conquered the duchy finally in 1230 but the city had possibly been conquered earlier. Afterwards, Plovdiv was conquered by Byzantium. According to some information, by 1300 Plovdiv was a possession of Theodore Svetoslav of Bulgaria. It was conquered from Byzantium by George Terter II of Bulgaria in 1322. Andronikos III Palaiologos unsuccessfully besieged the city, but a treaty restored Byzantine rule once again in 1323. In 1344 the city and eight other cities were surrendered to Bulgaria by the regency for John V Palaiologos as the
Plovdiv Airport and Frankfurt) in 2015 after two years of stable operation. The government have started the first concession procedure back in 2011, but there were no candidates for it. The second attempt for the concession was made in the spring of 2016 when the government have opened a tender for a 35 years concession of the airport, but the tender was shortly cancelled for non-compliance with European rules. In December 2016 the government opened the 3-rd tender for the concession. In the new procedure 3 companies have made the bid for the airport - Silk Road Plovdiv Airport, Consortium Plovdiv Airport