* Art movement: This refers to a group of artists working in a similar style or with shared philosophies (e.g., Impressionism, Cubism, Surrealism). This is probably the closest single answer.
* Art school/academy: This refers to an institution of learning dedicated to the teaching of art. (e.g., The École des Beaux-Arts, the Rhode Island School of Design)
* School of thought (in art theory/criticism): This refers to a particular approach or methodology in understanding and interpreting art. (e.g., Formalism, Marxism in art criticism)
So depending on what you mean, the best answer would be art movement, art school/academy, or school of thought.