Not really Malthusian. Agricultural societies had adapted to keep the population stable during normal times and bounce back in a generation or two after bad times. Those cultural adaptations stopped working when childhood mortality declined.

Useful land was a scarce resource in more civilized regions, while labor was cheap. Given enough land, subsistence farmers could easily feed themselves outside particularly bad years. But much of the land belonged to local elites, and commoners had to work that land to fund the pursuits of the elites.