Vasubandhu, also known as Vasumitra, was a prominent Indian Buddhist philosopher and one of the co-founders of Yogachara Buddhism. His teachings played a significant role in the spread and development of this school of Buddhism.

One of the key contributions of Vasubandhu to the spread of Yogachara Buddhism was his development and elaboration of the Yogachara doctrine. This doctrine, also known as the "mind-only" or "consciousness-only" doctrine, emphasizes the primacy of consciousness and the concept of emptiness. Vasubandhu expanded upon the teachings of his predecessor, Asanga, and provided a more systematic and comprehensive understanding of the Yogachara philosophy.

Vasubandhu's most famous work, the Abhidharmakosha, is a comprehensive treatise on Buddhist psychology and philosophy. In this text, he presents the Yogachara perspective on the nature of reality and the workings of the mind. This text became a central and authoritative source for the study and practice of Yogachara Buddhism, and its popularity contributed to the spread of this school of thought.

Furthermore, Vasubandhu's teachings also played a crucial role in reconciling the Mahayana and Theravada schools of Buddhism. He was able to bridge the gap between these two traditions by incorporating elements of both into the Yogachara doctrine. This helped to unite the Buddhist community and promote the spread of Yogachara Buddhism.

Vasubandhu's teachings also had a significant impact on the development of Buddhist meditation practices. He emphasized the importance of meditation in attaining enlightenment and provided detailed instructions on various meditation techniques. His teachings on meditation were widely adopted and practiced, which further contributed to the spread of Yogachara Buddhism.

Additionally, Vasubandhu's writings were instrumental in spreading Yogachara Buddhism to other parts of Asia. His works were translated into Chinese and Tibetan, making them accessible to a wider audience. His influence can also be seen in the development of other Buddhist schools, such as the Chinese Faxiang (Dharma-character) school and the Japanese Hosso (Yogachara) school.

In conclusion, Vasubandhu's teachings played a crucial role in the spread of Yogachara Buddhism. His development of the Yogachara doctrine, his influential writings, and his efforts to reconcile different Buddhist traditions all contributed to the popularity and growth of this school of thought. His contributions continue to be studied and revered by Buddhist practitioners around the world.