After the restoration of Bulgarian statehood by the brothers Assen and Peter, a period of gradual territorial expansion followed. Large territories dating from the First Bulgarian Kingdom, were reunited or annexed to Bulgaria. These events were accompanied by political development and economic and cultural revival. The scribe and art schools in Tarnovo perpetuated the traditions of the old Bulgarian culture. The Patriarch of Tarnovo kept gaining increasing authority in the Orthodox East.
Metallurgy also significantly developed. Construction and architecture are making a great leap forward. The number of fortresses in the Bulgarian territories reaches over 2 000, while the construction of the fortresses complied with the rule for quick communication between them, including the presence of posts transmitting visual signals. With these revolutionary steps, Bulgaria's defence system became one of the most innovative in Europe at that time.
The first Bulgarian minted coins came to be – out of gold, silver and copper. It was also the beginning of trade in goods with Dubrovnik and the Italian republics. Excluding sporadic external invasions and war with its neighbours, for a period of about two centuries, the Second Bulgarian Kingdom established itself as a leading military-political force in Eastern Europe.
However, internal disagreements and power struggles led to the division of the country into two factions - the Vidin Kingdom and the Tarnovo Kingdom. In the absence of consolidation, the invasion of the Balkans by the Ottoman Turks in the fourteenth century led to the collapse of the Second Bulgarian Kingdom in 1396.