The statement regarding the rulers of the Gupta Empire speaking Tamil is not accurate. The Gupta Empire, which flourished from approximately 320 to 550 CE, primarily used Sanskrit as its official language and was predominantly located in northern India. The empire was instrumental in the classical period of Indian culture, encompassing significant advancements in art, science, and literature. In contrast, Tamil is a Dravidian language spoken mainly in southern India and parts of Sri Lanka.
Regarding the spread of Indian cultural ideas and practices, it's true that trade networks played a significant role in this process. The Gupta Empire's influence extended beyond its borders through trade, which facilitated cultural exchanges between India and other regions, including Southeast Asia. Indian concepts of art, religion (especially Hinduism and Buddhism), and culture were transmitted along these trade routes, influencing various cultures across Asia.
In summary, while the Gupta Empire had a profound impact on Indian civilization and contributed to cultural diffusion via trade, it was not centered on Tamil language or culture, which is more closely associated with southern India and the later Chola and Pandya dynasties.