Although some former rulers of Bohemia had enjoyed a non-hereditary royal title during the 11th and 12th centuries (Vratislaus II, Vladislaus II), the kingdom was formally established in 1198 by Přemysl Ottokar I, who had his status acknowledged by Philip of Swabia, elected King of the Romans, in return for his support against the rival Emperor Otto IV.
In 1204 Ottokar's royal status was accepted by Otto IV as well as by Pope Innocent III.
It was officially recognized in 1212 by the Golden Bull of Sicily issued by Emperor Frederick II, elevating the Duchy of Bohemia to Kingdom status.

Under these terms, the Czech king was to be exempt from all future obligations to the Holy Roman Empire except for participation in the imperial councils.
The imperial prerogative to ratify each Bohemian ruler and to appoint the bishop of Prague was revoked.
The king's successor was his son Wenceslaus I, from his second marriage.

Wenceslaus I's sister Agnes, later canonized, was an extraordinarily courageous and energetic woman for her time; she refused to marry the Holy Roman Emperor and instead devoted her life to spiritual works.
Corresponding with the Pope, she established the Knights of the Cross with the Red Star in 1233, the first military order in the Kingdom of Bohemia.
Four other military orders were present in Bohemia: the Order of St. John of Jerusalem from c. 1160; the Order of Saint Lazarus from the late 12th century; the Teutonic Order from c. 1200–1421; and the Knights Templar from 1232 to 1312.

The 13th century was the most dynamic period of the Přemyslid reign over Bohemia.
German Emperor Frederick II's preoccupation with Mediterranean affairs and the dynastic struggles known as the Great Interregnum (1254–73) weakened imperial authority in Central Europe, thus providing opportunities for Přemyslid assertiveness.
At the same time, the Mongol invasions (1220–42) absorbed the attention of Bohemia's eastern neighbors, Hungary and Poland.

Přemysl Ottokar II (1253–78) married a German princess, Margaret of Babenberg, and became duke of Austria.
He thereby acquired Upper Austria, Lower Austria, and part of Styria.
He conquered the rest of Styria, most of Carinthia, and parts of Carniola.
He was called "the king of iron and gold" (iron because of his conquests, gold because of his wealth).
He campaigned as far as Prussia, where he defeated the pagan natives and in 1256, founded a city he named Královec in Czech, which later became Königsberg (now Kaliningrad).

In 1260, Ottokar defeated Hungary in the Battle of Kressenbrunn, where more than 200,000 men clashed.
He ruled an area from Austria to the Adriatic Sea.
From 1273, however, Habsburg king Rudolf began to reassert imperial authority, checking Ottokar's power.
He also had problems with rebellious nobility in Bohemia.
All of Ottokar's German possessions were lost in 1276, and in 1278 he was abandoned by part of the Czech nobility and died in the Battle on the Marchfeld against Rudolf.

Ottokar was succeeded by his son King Wenceslaus II, who was crowned King of Poland in 1300.
Wenceslaus II's son Wenceslaus III was crowned King of Hungary a year later.
At this time, the Kings of Bohemia ruled from Hungary to the Baltic Sea.

The 13th century was also a period of large-scale German immigration, during the Ostsiedlung, often encouraged by the Přemyslid kings.
The Germans populated towns and mining districts on the Bohemian periphery and in some cases formed German colonies in the interior of the Czech lands.
Stříbro, Kutná Hora, Německý Brod (present-day Havlíčkův Brod), and Jihlava were important German settlements.
The Germans brought their own code of law – the ius teutonicum – which formed the basis of the later commercial law of Bohemia and Moravia.
Marriages between Czech nobles and Germans soon became commonplace.
Although some former rulers of Bohemia had enjoyed a non-hereditary royal title during the 11th and 12th centuries (Vratislaus II, Vladislaus II), the kingdom was formally established in 1198 by Přemysl Ottokar I, who had his status acknowledged by Philip of Swabia, elected King of the Romans, in return for his support against the rival Emperor Otto IV. In 1204 Ottokar's royal status was accepted by Otto IV as well as by Pope Innocent III. It was officially recognized in 1212 by the Golden Bull of Sicily issued by Emperor Frederick II, elevating the Duchy of Bohemia to Kingdom status.
Under these terms, the Czech king was to be exempt from all future obligations to the Holy Roman Empire except for participation in the imperial councils. The imperial prerogative to ratify each Bohemian ruler and to appoint the bishop of Prague was revoked. The king's successor was his son Wenceslaus I, from his second marriage.
Wenceslaus I's sister Agnes, later canonized, was an extraordinarily courageous and energetic woman for her time; she refused to marry the Holy Roman Emperor and instead devoted her life to spiritual works. Corresponding with the Pope, she established the Knights of the Cross with the Red Star in 1233, the first military order in the Kingdom of Bohemia. Four other military orders were present in Bohemia: the Order of St. John of Jerusalem from c. 1160; the Order of Saint Lazarus from the late 12th century; the Teutonic Order from c. 1200–1421; and the Knights Templar from 1232 to 1312.
The 13th century was the most dynamic period of the Přemyslid reign over Bohemia. German Emperor Frederick II's preoccupation with Mediterranean affairs and the dynastic struggles known as the Great Interregnum (1254–73) weakened imperial authority in Central Europe, thus providing opportunities for Přemyslid assertiveness. At the same time, the Mongol invasions (1220–42) absorbed the attention of Bohemia's eastern neighbors, Hungary and Poland.
Přemysl Ottokar II (1253–78) married a German princess, Margaret of Babenberg, and became duke of Austria. He thereby acquired Upper Austria, Lower Austria, and part of Styria. He conquered the rest of Styria, most of Carinthia, and parts of Carniola. He was called "the king of iron and gold" (iron because of his conquests, gold because of his wealth). He campaigned as far as Prussia, where he defeated the pagan natives and in 1256, founded a city he named Královec in Czech, which later became Königsberg (now Kaliningrad).
In 1260, Ottokar defeated Hungary in the Battle of Kressenbrunn, where more than 200,000 men clashed. He ruled an area from Austria to the Adriatic Sea. From 1273, however, Habsburg king Rudolf began to reassert imperial authority, checking Ottokar's power. He also had problems with rebellious nobility in Bohemia. All of Ottokar's German possessions were lost in 1276, and in 1278 he was abandoned by part of the Czech nobility and died in the Battle on the Marchfeld against Rudolf.
Ottokar was succeeded by his son King Wenceslaus II, who was crowned King of Poland in 1300. Wenceslaus II's son Wenceslaus III was crowned King of Hungary a year later. At this time, the Kings of Bohemia ruled from Hungary to the Baltic Sea.
The 13th century was also a period of large-scale German immigration, during the Ostsiedlung, often encouraged by the Přemyslid kings. The Germans populated towns and mining districts on the Bohemian periphery and in some cases formed German colonies in the interior of the Czech lands. Stříbro, Kutná Hora, Německý Brod (present-day Havlíčkův Brod), and Jihlava were important German settlements. The Germans brought their own code of law – the ius teutonicum – which formed the basis of the later commercial law of Bohemia and Moravia. Marriages between Czech nobles and Germans soon became commonplace.
Kingdom of Bohemia