The primary reason for france and japan were interested in controlling parts of indochina in the 20th century was 1.-dominate the indian ocean. 2.-obtain valuable natural resources. 3.-stop the spread of communism. 4.-prevent spanish colonization.

2. Obtain valuable natural resources.

Explanation:

The main reason for the interest of France and the japan in order to control over the Indo and china was the availability of the resources in the country as the period of the 20th century was marked as the period of the large scale growth in terms of the trade and commerce and this lead to the economic diversity of the nation as form 1930 the France started to exploit this region for the tea, rice, the coffee, the pepper, the coal, and the zinc.

Empty quarter and sandy desert