What did the Mongol Warriors carry during the conquests?
Mongolian military had a decimal system. The smallest unit was 10 (aravt). Ten aravts became one hundred (zuun). Ten zuuns became thousand (myangat). Ten myangat became 10,000 (tumen).
I think this part of Mongolian military trivia everybody is aware of. But do you know why was it set up this way?
Each soldier meant one family. So Myangat meant, not only 1,000 strong military unit, it also meant one thousand families, most probably from one tribe. The way Mongolian census worked was each Ger(dwelling) represented one unit. So when Mongolian khans went to wars, the order was for each family to provide one soldier. One family, one soldier. And the khans knew how many families each tribe had, because they had census data.
When Chinggis khan became the ruler of Mongols, he broke down all the tribes and clans. Each nobility was allocated certain number of families. For example, Chinggis Khan allocated 8,000 families to his second son Tsagaadai, 5,000 families to his third son Uguudei, 5000 to youngest son Tului. His mother and brother received one tumen each (10,000 families each). So Uelun, Chinggis Khan’s mother had to put forward up to 10,000 soldiers.
Chinggis Khan instituted Ikh Khurildai, a gathering of nobility, military leaders, a kind of modern day parliament. During Ikh khurildai, they would discuss who they would fight against, how many soldiers each noble was supposed to provide etc. Upon deciding where to attack, the spies would start to collect information. How many watering holes were on the way, how much grass was available, the number of enemy units, how cities were protected etc. In some cases, wells would be dug in advance.
The expeditions usually started with the first snow, as the horses were the strongest, the loot the biggest. The health of horses was very important, therefore taking care of them was paramount. Chinggis khan wouldn’t start expedition unless the horses were rested and ready.
To prepare for war each family was required to prepare clothes, both warm and cold, weapons, armor, at least 4–5 horses, food such as dried meat, dried milk products, cheese etc, sewing kit, sharpening stone, small tent etc. There was a fairly long list of what was required to prepare. So a soldier was prepared for war by his family. His unit commander, most probably their neighbor or relative, made sure that the soldiers were sufficiently trained for war. They would periodically mobilize the soldiers, in order to keep them combat ready. Since soldiers, also, grew up together in one tribe, they had an unparalleled unit cohesion.
Each soldier carried enough food to last months. For example a whole cow could be slaughtered dried, crushed and pummeled until you could carry it in a small sack. It would then be boiled in water with some flour and made soup. It was the Mongolian version of instant noodles.
Since expeditions lasted months, sometimes years, the initial rations would eventually run out. Soldiers would first take the food from the locals. This, however, became problematic as the enemies learned Mongol tactics and would burn everything. Therefore, Mongols started to prepare food on a large scale. For example, in 1206 Chinggis khan gave order to grow grains to the west of Mongolia. For that purpose, they dug up hundreds of wells to water them. Also flour mills, storage units were created.
Livestock, such as sheep, goats, cows, would also be sent with soldiers. On long expeditions, wives and children would also travel with the soldiers. They would bring their own livestock.
The elite bodyguard of Chinggis Khan, the Khishigten, was fed clothed and armed by the royal family.
Их Монгол улс — Википедиа нэвтэрхий толь
Их монгол Улсын цэргийн ар тал, ахуй хангалт
 The Mongols in World History