Historical geographical term used primarily before and during WWII to refer to the central region of China. The kanji 支那 is now widely regarded as a derogatory name for China, and this term is no longer used in modern Japanese except in historical discussions.
On pre-war maps, the notation 'Central China' can be seen.
In history class, we learned about the 'Central China Expeditionary Army'.
Compound of 中 (naka, 'central') and 支那 (Shina, an old name for China derived from 'China' via Western languages). The term fell out of use after WWII due to the derogatory connotations of 支那.