In Yogachara Buddhism, the concept of "mind-only" refers to the belief that all phenomena, both external and internal, are ultimately created by the mind. This concept is also known as "cittamatra" in Sanskrit, which translates to "mind-only" or "mind-only school."

Asanga, the founder of Yogachara Buddhism, explained this concept through the teachings of the Lankavatara Sutra and the Yogachara-bhumi Shastra. He believed that the mind is the primary source of all experiences and perceptions, and that the external world is merely a projection of the mind.

According to Asanga, the mind is constantly creating and projecting mental images, which are then perceived as external objects. This process is known as "vijnapti-matra," or "representation-only." He argued that the mind creates these representations based on past experiences and impressions, and that they are not necessarily reflective of an objective reality.

Asanga also emphasized the importance of understanding the true nature of the mind in order to attain enlightenment. He taught that the mind has two aspects - the "defiled" or "impure" aspect, and the "pure" or "enlightened" aspect. The defiled aspect is the source of suffering and delusion, while the pure aspect is the source of wisdom and enlightenment.

In order to overcome suffering and achieve enlightenment, Asanga taught that one must cultivate the pure aspect of the mind through practices such as meditation, mindfulness, and the cultivation of compassion and wisdom. By doing so, one can gradually purify the mind and gain insight into the true nature of reality.

Furthermore, Asanga also explained the concept of "alaya-vijnana," or the "storehouse consciousness," which is the repository of all past experiences and impressions. This consciousness is seen as the source of the defiled aspect of the mind, but through spiritual practice, it can also be transformed into the pure aspect.

In summary, the concept of "mind-only" in Yogachara Buddhism is based on the belief that the mind is the primary creator of all experiences and perceptions. Asanga explained this concept through the teachings of the Lankavatara Sutra and the Yogachara-bhumi Shastra, emphasizing the importance of understanding the true nature of the mind and cultivating the pure aspect in order to attain enlightenment.