While oil painting, which was introduced to Japan in the Meiji period, is called Yo-ga (foreign style painting), Nihon-ga refers to paintings which utilize traditional Japanese techniques and styles and rather than being reliant on oil paint.
明治時代に日本に導入された油絵を「洋画」と呼ぶのに対して、油彩に依らず、それまでの日本の伝統的な技法や様式の上に育てられた絵画を指す。