The power of the Eastern Roman Empire has again waned by 1185 because of external conflicts.

The noble brothers Asen and Peter lead a revolt that forces imperial recognition of an autonomous Bulgarian state.

Centered at Turnovo (present-day Veliko Turnovo), this state becomes the Second Bulgarian Empire.

Like the First Bulgarian Empire, the second expands at the expense of a preoccupied Byzantine Empire.

In 1202 Tsar Kaloian (1197-1207) concludes a final peace with Constantinople that gives Bulgaria full independence.

Kaloian also drives the Magyars from Bulgarian territory and in 1204 concludes a treaty with Rome that consolidates Bulgaria's western border by recognizing the authority of the pope.

By the middle of the thirteenth century, Bulgaria again rules from the Black Sea to the Adriatic.

Access to the sea greatly increases commerce, especially with the Italian Peninsula.

Turnovo becomes the center of Bulgarian culture, which enjoys a second golden age.

The final phase of Bulgaria's second Balkan dominance is the reign of Kaloian's successor, Ivan Asen II (1218-41).

In this period, culture continues to flourish, but political instability again threatens.

After the death of Ivan Asen II, internal and external political strife intensify.

Sensing weakness, the Tatars begin what will; be sixty years of raids in 1241, the Byzantines retake parts of the Second Bulgarian Empire, and the Magyars again advance.

Isaac fails to crush the revolt of the Bulgarians and Vlachs, even though he leads expeditions against them in 1186-87.

The Asen brothers regroup, obtain the support of the Cumans, and launch a series of devastating raids against the empire in Thrace and Macedonia.

The brothers check the imperial army in Thrace in 1187; and, in the armistice that follows, which forces Constantinople’s recognition of an autonomous Bulgarian state, …

…their younger brother Kaloyan is sent as hostage to Constantinople.

He escapes, however, and war with Bulgaria breaks out, to continue intermittently.

In other developments, Constantinople patches things up with Venice in 1187.

Peter is killed by the boyars a year after he ascends the Bulgarian throne.

His younger brother Kaloyan is then crowned tsar.

Kaloyan has pursued his predecessors' aggressive policy against the Empire to the point of making an alliance with Ivanko, who had entered imperial service in 1196 and had become governor of Philippopolis (Plovdiv).

Another ally of Kaloyan is Dobromir Hriz (Chrysos), who governs the area of Strumica.

The coalition is quickly dissolved, as the imperial forces overcome both Ivanko and Dobromir Hriz.

Nevertheless, …

…Kaloyan conquers from the Empire Konstanteia (Simeonovgrad) in Thrace and …

…Varna in 1201, and will take most of Slavic Macedonia in 1202.

The Second Bulgarian Empire expands, like the first, at the expense of a preoccupied Constantinople.

In 1202, Tsar Kaloyan concludes a final peace with the Empire that gives Bulgaria full independence.

The foundations of the Second Bulgarian State, with Tarnovo as its capital, had been laid as a result of the successful uprising of the brothers Peter IV and Ivan Asen I in 1185/1186.

Following Boris I’s principle that the sovereignty of the state is inextricably linked to the autocephaly of the Church, the Asen brothers had immediately taken steps to restore the Bulgarian Patriarchate.

As a start, they established an independent archbishopric in Tarnovo in 1186.

The struggle to have the archbishopric recognized according to the canonical order and elevated to the rank of a Patriarchate will take almost fifty years.

Following the example of Boris I, Bulgarian Tsar Kaloyan, a younger brother and heir of Peter IV and Ivan Asen I, has maneuvered for years between the Patriarch of Constantinople and Pope Innocent III.

King Emeric of Hungary had invaded Bulgaria in 1202 and conquered the areas of Belgrade, Braničevo (Kostolac), and Niš (which he turned over to his protégé on the throne of Serbia, Vukan Nemanjić).

Kaloyan had retaliated in 1203, restoring Vukan's brother Stefan Nemanjić in Serbia and recovering his lands after defeating the Hungarians.

Ill feeling between Bulgaria and the Hungarians continues until the intercession of Pope Innocent III, who had written to Kaloyan, inviting him to unite his Church with the Roman Catholic Church, as early as 1199.

Wanting to bear the title of Emperor and to restore the prestige, wealth and size of the First Bulgarian Empire, Kaloyan had responded in 1202.

In this political maneuver, he had requested that Pope Innocent III bestow on him the imperial crown and scepter that had been held by Simeon I, Peter I, and Samuel and in exchange he might consider communication with Rome.

Kaloyan had also wanted the Papacy to recognize the head of the Bulgarian Church as a Patriarch.

The pope is not willing to make concessions on that scale, and when his envoy, Cardinal Leo, arrives in Bulgaria, he anoints the Archbishop Vasilij of Turnovo as Primate of Bulgarians and Vlachs.

Kaloyan only receives a Uniate crown as rex Bulgarorum et Blachorum ("King of Bulgarians and Wallachians") or rex Bulgarie et Blachie ("King of Bulgaria and Wallachia"), not emperor.

Blithely, Kaloyan writes to the pope, thanking him for an imperial coronation and for the anointing of his patriarch.

He also assures him that he too will follow the Catholic Church rites, as part of the agreement.

Meanwhile, in an attempt to foster an alliance with Kaloyan, Emperor Alexios III Angelos recognizes his imperial title and promises him patriarchal recognition.

The union with the Roman Catholic Church will continue or well over three decades.