All (well, almost) you always wanted to know about districts in Bohemia, Moravia and Silesia. Or at least those important bits which could make your research a bit easier. Not much, but at least a bit. The districts as we know them were created in the middle of 19th century, during huge administrative reform initiated by the Emperor František Josef I. Czech lands were divided into several regions and number of domains before this reform.
Situation before 1850
Bohemia, Moravia and Silesia were divided into 24 regions - 16 of them in Bohemia, 6 in Moravia and 2 in Silesia. These regions are not often mentioned in the parish books, more often there is mentioned to which domain people belonged as serfs.
Regional division before 1850.
For example berní rula, first Bohemian (not Moravian or Silesian) list of householders from the second half of 17th century, is based on this regional division.
Situation 1850 to 1855
The administrative reform took place in 1849/1850 when district were created. There were two types of districts - political and court districts. And they didn't match. There were more court districts than there were political districts. Political districts were often called hejtmanství, court districts just soud (which stands for court).
Regional and district division 1850-1855.
There were 7 regions, 79 political districts and 208 court districts in Bohemia, 2 regions, 25 political districts and 77 court districts in Moravia and 1 region, 7 political districts and 22 court districts in Silesia. There is wonderful table showing the division on Pěnkava and Kraus genealogy website (in English).
For example under Smíchov political district belonged court districts Smíchov, Zbraslav, Unhošť and Beroun. And it all belonged under Prague region. Or under Hustopeče political district belonged court districts Břeclav, Hustopeče, Židlochovice and Klobouky - and it all belonged under Brno region.
Situation 1855 to 1868
This division was waaaaay too complicated. So it was decided in 1855 to integrate the court and political districts into one district office. This meant also integrating both judicial and political power which never works too well. Anyway this division was in place for 13 years before it was decided another change is needed to be done and that those two powers have to be divided.
Regional division as on 1930.
Situation 1868 to 1949
There were political districts (hejtmanství) created again with the district courts as independent offices. There again were more court district offices than political district offices. Why? To make courts available and reachable to anyon, even by foot. Don't forget that many people still travelled by foot in the second half of 19th century and first half of 20th century.
District offices in 1900. Source: Wikimedia
This division was in place till 1949 when modern regions and districts were created.
Sources to use
Seznam míst v Království českém - huge book covering all places (even hamlets) in Bohemia. Available in PDF from Google Books or in Kramerius of Czech National Library.
Geography lecture from Olomouc university (PDF, in Czech)
Color maps taken from an article by L. Jeleček: Územněsprávní reformy v Česku v letech 1848-2000. In: Geografické rozhledy no. 9, 1999/2000.