In the Mantaro Valley, one of the largest fertile growing regions of the Inca Empire, archeologists have found 2,573 qullqas (storehouses). These could hold 170,000 square meters of goods. Some of this was for non-food storage, but a ton of it was dried potatoes, quinoa, etc. When the Spanish showed up, the Inca equipped and fed a 35,000 man army from the storehouses around the Mantaro Valley.
But these qullqas were spread around the empire, and other areas stored corn, seaweed, dried fish, etc.
I can't think of another civilization that had such huge reserves on hand to deal with emergencies. When I think of medieval Europe, famine and starvation seem to pop up every few years.
So was this unique? Did anyone else prepare for famines on this scale?
The Inca had a complex and vast supply of storehouses across their entire empire; though it’s an extremely common (but not wholly correct) view that these were to mitigate times of famine - the storehouses were more important for their supply of finished textiles and raw fiber, as the Inca viewed cloth as one of the most important parts of their culture especially in terms of economy (similarly to strip woven cotton being used as “money/cash” in West Africa pre colonization). It has been recorded that in battle, Inca at war would strip the enemy of their cloth and bring it back to their storehouses, or even burn their own storehouses if retreating so that the enemy would not have the tactical advantage of replacing warm clothing during battle in the Andean mountains. Cloth was the bread and butter of the Inca.
That said, with unequal water supply, soil conditions, and crop yield in the Andes, the storehouses were necessary to feed all people, all the time. it has been suggested that the storehouses acted as a continuous flow of food and cloth rather than an emergency situation; obviously there were excess stores for harder times, it was not their primary function. Considering that the best farm land in the andes was closer to sea level, crops would be transported to the storehouses for “equal” dispersement (affected of course by warring factions). It was just the smartest way to use resources.
(“cloths function in the Inca State” by Annette B Weiner and Jane Schneider, covers this exceptionally well with log books from the Spanish and recorded oral histories written by the Spanish as they interacted with the Inca, which we must also look at with critical lenses)
As far as other civilizations having storehouses- yes and no. All civilizations pre-industrialism would have stores of food and other raw materials, as these were collected as tax for a very long time. It could be dispersed (or not) at discretion by the ruling class. The Inca system was the most highly developed, or at least our most well documented large example.
One point of interest would be the Japanese (specifically yayoi, heian, and edo period) kura, naya, and koya, which stored things like ceremonial items, mundane items, rice and other dried goods, respectively. Japanese homes have traditionally always lacked storage, which necessitated the existence of somewhere to keep your things. They do seem to noted more for their protection and keeping of religious and ceremonial paraphernalia, however.
(The japanese storehouse, Marc Treib, Journal of the Society of Architectural Historians (1976) 35 (2): 124–137.)
The Minoans most likely saw the storage of surplus goods as key to power, which is illustrated by the palace storage at knossos, but again, any civilization worth its salt would have stores, be it a communal pit, shed, or large building- its the predecessor to the modern warehouse. The inca storage system seems to be unprecedented and pretty unique, until modern times.