What is "donghak"

Donghak (lit. Eastern Learning) was an academic movement in Korean Neo-Confucianism founded in 1860 by Choe Je-u. The Donghak movement arose as a reaction to seohak (, "Western learning"), and called for a return to the "Way of Heaven". While Donghak originated as a reform movement and revival of Confucian teachings, it gradually evolved into a religion known today as Cheondoism in Korea under the third patriarch.