In the context of Indian history, the principle of “Dyarchy (diarchy)” refers to –

The principle of Dyarchy was introduced by the Government of India Act of 1919 in the provinces of British India.

This system divided the functions of government into two categories central and provincial.

The provincial subjects were further subdivided into transferred and reserved.

Thus, the principle of Dyarchy refers to the division of the subjects delegated to the provinces into two categories.