Nitrogen was a limiting factor in human civilization since it started. You can only feed so many people on the same soil even with farm animal poop. Guano was an way around that limiting factor. It was a valuable natural resource like oil or rare earth metals are today. Civilizations like the Incas had it and thrived. Those that didn't couldn't stay in one place for too long. It was set to be the cause of the first world war, but the Haber-Bosch process was invented in 1906. That allowed energy from oil to grow crops in depleted soil. It prevented war, but is also the single greatest contributor to climate disaster since agriculture itself.