RE: Columbus and the Spice Trade (repost)
Spices were the petroleum of the ancient/medieval era. During the Age of Sail, it may be argued that food preservation (meat) was the limiting factor to mercantile expansion, as wind is an unlimited propellent with the quantity in storage of food and water being the only limitation to the range of a sailing vessel. Later, with the coal-powered and petrol-driven ships, the limiting factor to range of a vessel became the quantity of fuel, rather than perishable food items. In our nuclear era, the limitations of shipping operation returned to the nutritional health of the sailors, which was overcome by Linus Pauling's elucidation of the Vitamin C chemical structure, leading to the possibility of unlimited nuclear submarine warfare and MAD.
The trade imbalance between the West and the East had profound impact upon China (don't know about India). The massive influx of silver into the Chinese economy, already short in precious metals, including copper, eventually lead to the Chinese using silver as de facto currency medium. I recall, even as a child in the 20th century, of the perception in the East of the ready availability of silver as medium for bauble manufactures.
The silver glut in China led to two Opium wars, from which the West attempted some rational trade balance to prevent the massive silver drain towards the East. More importantly, with the independence of the South American colonies from European rule, the silver flow stopped, and the Chinese, lacking a ready supply of their de facto currency medium witnessed the collapse of the Qing central government. Any polity without absolute control over their currency has not long before its inevitable collapse. From the British perspective, the Opium wars were necessary intervention to prevent their central government from devolving into the chaos Qing fell into, during the late 19th century (or maybe it is just a rationalization of the British in their unethical wars to peddle drugs that kept millions of Chinese addicted).