The oldest known member of the family at the end of the 12th century was Smil Světlík from Tuháň. However, it is not documented whether it is Tuhaň, located approximately 4.5 km west from
Dubá in
Česká Lípa District, or Tuhaň in
Slaný, which is now in the territory of
Kladno-Švermov. The opinions of historians starting with
František Palacký differ. At the beginning of the 13th century, Smil held Vojnica near Libochovice. He and his sons Jindřich and Častolov are mentioned in the years 1200–1227 as owners of various settlements in the northern part of today's central
Bohemia, e.g.
Lovosice,
Klapý,
Libochovice. Smil died sometime around 1216. Častolov was listed as the son of Smil for the first time in 1216, while 10 years later he is listed as the highest hunter (
Czech:
nejvyšší lovčí). Jindřich, the second and younger of the sons, was mentioned for the first time (along with his brother) in 1219 as a witness to a document of
Ottokar I of Bohemia for the monastery in
Plasy. In 1232, he became a
castellan at the royal castle of
Bautzen, where he remained until 1237. Together with his brother Častolov and with the help of the Czech king
Wenceslaus I, they acquired the territory of
Zittau and after 1238 are mentioned in documents with the surname
de Sitavia ("from Zittau"). The brothers managed to acquire a large piece of territory stretching from
Pirna to the foothills of the
Lusatian Mountains up to
Česká Lípa, which became the family's power base. Apparently, they chose their name in Zittau, in the
Lusatian Neisse valley, today in
Polish territory. The eponymous
Ronov Castle in the south of Česká Lípa was built almost 150 years later, at the end of the 14th century. The people of Ronov also gave the name Ronov to other castles they built. ==The rise to power of the Ronovci==