Indian and Tibetan epistemologists have spent millennia grappling with the central philosophical questions of relativism and intersubjectivity. This talk will present my ongoing DPhil research that attempts to map a philosophical history of the discussion, by focussing on a specific Buddhist example that problematises perceptual relativism. This classic Buddhist example is the perception across world spheres of a river, which depending on the realm one belongs to, will be perceived as either blood for hungry ghosts, water for humans, or nectar for the gods. The story begins in India with a brief map of the chronological and philosophical developments of the example. Next, the discussion shall survey the major Tibetan exegetes of Madhyamaka philosophy over the last millennia, and specifically those who use the example. Finally, we will zoom inwards to focus on a specific debate surrounding a highly controversial interpretation of the example by Tsongkhapa (1357-1419).