Step 1: The Language Barrier:
Al-Biruni, an $11^{\text{th}}$-century Persian polymath, noted that Sanskrit was completely different from Arabic and Persian. Sanskrit has a highly complex grammar, distinct phonetic rules, and terms that contain multiple levels of meaning. This made translating abstract philosophical and scientific works into Arabic extremely difficult.
Step 2: Cultural, Religious, and Customary Differences:
Al-Biruni observed that the religious and social practices of $11^{\text{th}}$-century India were entirely foreign to his own Islamic background. These differences in everyday customs and social organization created a psychological gap, making it difficult for an outsider to interpret local behaviors without bias.
Step 3: Ethnocentrism and Social Insularity:
He wrote that the local people, especially the Brahmins, were highly insular, calling foreigners mlechchhas (barbarians or unclean). This social distance meant that Indian scholars were reluctant to share their scientific and philosophical knowledge with foreigners, cutting Al-Biruni off from direct intellectual exchange.