So, you know how you have a ruler at school or a leader in your scout group? Well, countries also have leaders. One big country called Mexico has many states, like how your school has many grades. One of those states is called Sonora.
Now, long long ago, some people in Sonora wanted to have their own government and not be ruled by the big government in Mexico City. They wanted to make their own rules and laws and have their own leaders that they got to choose. So, they made a place called the "Republic of Sonora".
It was sort of like playing make-believe or pretend with your friends, but for real grown-up people. They had their own flag, their own army, and even made their own money!
But, eventually, the government in Mexico City didn't like that Sonora was acting like its own country and they put a stop to it. Now, Sonora is still a state in Mexico, but they get to have their own governor and make some of their own rules.
So, the Republic of Sonora was a time when the people in Sonora wanted to be their own country and it was like playing make-believe, but it didn't last forever.