# Particle in an infinite potential well

In quantum mechanics we have the system of an infinite potential well and then we find out the energy of the particle inside the well using Schrödinger's equation which gives,

$$E=\frac{n^2π^2\hbar^2}{2ma}.$$

I was wondering where does the particle inside the well come from? Was it always there? Can there be particles in the region of infinite potential?

Edit: From the answer, suppose we have a particle outside the well which has energy greater than the outside potential. Now, according to the inside of the well both the outside potential and the outside particle have an infinite parameter. So can this particle enter the well?