When a group of people get together and agree to do something, sometimes they write down their agreement so everyone can remember what they said. This is called a "contract".
A long time ago, in 1895, some important people got together at a fancy hotel called Mohonk Mountain House. They were worried about wars and fighting between countries, and they wanted to find a way for countries to work together and talk things out instead of using violence.
So they wrote down an agreement, which is like a contract, that said they would all try to work together to solve problems peacefully. They called it the "Mohonk Agreement". It was important because it was one of the very first times that people from different countries got together and agreed to work towards peace.
Today, lots of people still talk about the Mohonk Agreement and use it as an example of how countries can work together instead of fighting.