Name a civilization which...
You know what? You're right. Private property is not required for civilization. All the thousands of years of preceeding human history teach us nothing, and the ideas of a thirty year old coffee shop Bohemian will change the world if we just hold hands and believe.
Private property is a fairly new development. If it's owned by your monarch, and he decrees that your local nobleman gets some land, then it's not really private property. Unless your entire kingdom is a piece of private property.
I respectfully disagree. A feudal kingdom was more like a real estate pyramid scheme than anything else.
The person of the King owned the kingdom. He 'leased' large areas of lands to nobles through the system of vassalage who paid rents and tithes up, usually in the form of military service. These nobles sub-leased smaller amounts of land down to the level of knights, which were incidentally receiving just enough land for one person to personally manage effectively. These knights leased their land down to the people who actually worked it, who keep whatever is in excess of their rents.
This is akin to the bank lending money to my father who pays the mortgage on the farms which he's bought and then rents to the farmers who actually work it. The farmers pay rent and keep whatever they make exceeding the rent. He makes a tidy profit as the middle man by taking on risk for the investment. The bank makes a profit earning interest paid. The bank owns the farm, but never touches it, just as a king owns the fields, but never sets foot on it. Through capitalism, landless farmers aquire land to work, a man who amassed some decent money through his professional career is now set to retire on his investment, and the bank would be making money had it not been stupidly pushed into the high-risk housing market by the Fed.
The theory of the Communists may be summed up in the single sentence: Abolition of private property.
KARL MARX, The Communist Manifesto
Communism, however, has no sense of private property. The land is just there. Who farms it? Whoever wants to. What do they get in return? Their rationed eggs, milk and flour. What if they work harder, increase yields, and produce a great surplus of food for the village? They get their rationed eggs, milk and flour, are called good communists, and the surplus goes to the city. What if they farm poorly, crops wither, and there's a shortage of food? Rationed eggs, milk and flour.
The bank picks the best person to give capital to, the capitalist picks the best tenants to rent, and the tenants put their backs into it, knowing their best efforts reap the best rewards for themselves. The state gives the capital to everyone, the commune director asks for volunteers, and whoever feels like farming does so knowing hard work isn't rewarded beyond a pat on the back. That is why communism fails.