linguistic:translation, stylistic:style_transfer, structural:scholar_edition
Ternopil Oblast, also referred to as Ternopilshchyna or Ternopillia, is an oblast (province) of Ukraine. Its administrative center is Ternopil, through which flows the Seret, a tributary of the Dniester. Population: 1,021,713. One of the natural wonders of the region are its cave complexes. Although Ternopil Oblast is among the smallest regions in Ukraine, over 100 caves have been discovered there. Scientists believe these are only 20% of all possible caves in the region. The biggest cave is Optymistychna Cave. Measuring 267 km (166 mi) in total length, it is the longest cave in Eurasia and the fifth-longest in the world. Twenty percent of the land in the region is chernozem soil. Among its attractions, Ternopil Oblast has 34 castles. By at least one account, the most prominent is the Zbarazh Castle with fortifications that expand over 16 ha and was the center of a 17th-century standoff between troops of Bohdan Khmelnytsky and the army of the Polish–Lithuanian Commonwealth. The Dniester Canyon passes through the oblast; it is considered one of the wonders of Ukraine, stretching for 250 km (160 mi).