The Czech lands had been settled by the Celts (Boii) from 5th BC until 2nd AC, then by various Germanic tribes (Marcomanni, Quadi, Lombards and others) until they moved on to the west during the Migration Period (1st-5th century). At the beginning of the 5th century the population has decreased vigorously and the first Western Slavs came in the second half of the 6th century, according to mythology led by a chieftain Čech. In the course of the decline of the Great Moravian realm during the Hungarian invasions of Europe in the 9th an 10th century, the Czech Přemyslid dynasty established the Duchy of Bohemia. Backed by the East Frankish kings, they prevailed against the reluctant Bohemian nobility and extended their rule over the adjacent Moravian lands, which were incorporated as a margraviate in 1182.
In 1198 Duke Ottokar I of Bohemia received the royal title by the German anti-king Philip of Swabia. German colonists settled in the mountainous border area on the basis of Bohemian kings' invitation during the Ostsiedlung from the second part of 13th century onwards (in Prague they lived already from the early 12th century) and lived alongside the Slavs.
The Silesian lands along the Oder River in the north had been ruled by the Polish Piast dynasty from the 10th century onwards. While Bohemia rose to a kingdom, the Duchy of Silesia fragmented into numerous principalities, which in the early 14th century came under the influence of the House of Luxembourg, Bohemian kings since 1310. The Polish king Casimir III the Great officially renounced Silesia by the 1335 Treaty of Trentschin.
At the same time, the Luxembourg kings also incorporated the lands of Lusatia (i.e. Upper and Lower Lusatia) in the northwest, however, 300 years later these territories passed to the Electorate of Saxony by the 1635 Peace of Prague. After the Bohemian Crown (Crown of Saint Wenceslas) passed to the Austrian House of Habsburg in 1526, the crown lands became part of the larger Habsburg Monarchy.
Alternate names 
The term Czech lands (České země) has been used to describe different things by different people. While the Czech name of Bohemia proper is Čechy, the adjective český refers to "Bohemian" and "Czech".
Some sources use the term to mean any territory ruled by the Kings of Bohemia, the Lands of the Bohemian Crown (země Koruny české) as established by Emperor Charles IV in the 14th century. This would include territories like Lusatia (most of which is now in Germany) and the whole of Silesia, all of which were ruled from Prague Castle at that time. Most Czech historical texts use the term in this manner[which?] when discussing the Middle Ages.
Other sources use the term to refer only to the core Czech areas of Bohemia, Moravia and former Austrian Silesia, which remained with the Bohemian Crown after the bulk of the Silesian lands had been conquered by the Prussian king Frederick the Great in 1742. For many topics, a distinction between the two definitions is not necessary, as since the loss of Silesia in the 18th century the remaining Lands of the Bohemian Crown have been more-or-less co-extensive with the territory of the modern-day Czech Republic.
The non-auxiliary term (i.e. the term used in official Czech geographical terminology lists) for the Czech part of the Czech lands (i.e. Bohemia, Moravia, Czech Silesia) is Česko, documented as early as in 1777. Today, it is also the official short form for the Czech Republic. Česko and its foreign equivalents (German: Tschechien, in distinction to former derogatory Tschechei) are also the terms officially preferred by the Czech Ministry of Foreign Affairs since 1993. However, "Czechia" has not caught on among English speakers. The term Česko had likewise run into temporary resistance from Czech speakers but has more recently caught on with many natives.
Coats of arms 
The coat of arms of the Czech Republic incorporates the coats of arms of the three integral Czech lands: Bohemia proper, Moravia and Czech Silesia. The arms of Bohemia originated with the Bohemian kingdom, like the arms of Moravia originated with the Moravian margraviate. And finally, the arms of Czech Silesia originated as the arms of all of the historical region of Silesia, much of which is now in Poland.
See also 
- History of the Czech lands
- Kingdom of Bohemia
- List of rulers of Bohemia
- Lands of the Bohemian Crown
- Protectorate of Bohemia and Moravia
- Pánek, Jaroslav; Tůma Oldřich et al. (2009). A History of the Czech lands. Prague: Karolinum. ISBN 978-80-246-1645-2.