Indochina = India-China, which refers to the region between India and China.
"Zhina" (支那) is similar to "Zhendan" (震旦), both being ancient transliterations of China from Tianzhu (India).
The term "Zhina" originates from the transliteration of "Cina" and was the ancient name used in India to refer to ancient China, first appearing in Sanskrit Buddhist scriptures. The Sanskrit word "Cina" entered different languages with little change in pronunciation, being transliterated as "China," "Zhina" (支那), "Zhi-na" (脂那), "Zhi-na" (至那), or "Zhendan" (震旦).