text: Geography Borsod–Abaúj–Zemplén is one of the most geographically diverse areas of Hungary. It lies where the Northern Mountains meet the Great Hungarian Plain, thus the northern parts of the county are mountainous – with some of the highest peaks and deepest caves in the country – the southern parts are flat. The average temperature is lower than that of the country, the average humidity is higher (7–800 mm/year.) The region holds the country's record for lowest temperature:  on 16 February 1940 in the town of Görömböly-Tapolca (now Miskolctapolca.)
  Rivers
  Tisza, which forms a natural border between Borsod-Abaúj-Zemplén and Szabolcs-Szatmár-Bereg countries
  Sajó, a tributary to Tisza
  Bodrog, a tributary to Tisza
  Hernád, a tributary to Sajó
  Highest points
  Istállós-kő, Bükk Mountains (959 m.)
  Nagy-Milic, Zemplén Mountains (894 m.)
  History
  Borsod–Abaúj–Zemplén county was created after World War II from the pre-1938 counties Borsod–Gömör–Kishont, Abaúj–Torna and Zemplén (see also: 1950 Administrative Reform in Hungary).
  From the Conquest until the Turkish occupation (900s–1526)
  The historical comitatus (Hungarian: vármegye – "castle county", since each of them belonged to a castle) came into existence during the Middle Ages. Borsod county belonged to the Castle of Borsod, Abaúj belonged to the Castle of Újvár (in the modern village of Abaújvár) and Zemplén belonged to the Castle of Zemplén (today in Slovakia.)
  At this time the area of Borsod also included the later county Torna, and Abaúj also included the later counties Sáros and Heves. In the 12th century the former Abaúj comitatus was split into Abaúj, Heves and Sáros counties, while Torna was separated from Borsod. For the next hundreds of years the borders remained unchanged.