Hello, Coder! This unit's exciting programming lesson will involve traversing the labyrinth of two-dimensional matrices. We're going to apply our TypeScript skills to combine submatrices from two different matrices, creating a new one. It might appear to be quite a complex task, but don't fret! We'll go through this together, one step at a time, and by the end of the lesson, you'll be a matrix master.

Are you ready for the task? Here it is: imagine having two different 2D arrays, A and B. Our job is to devise a TypeScript function — let's name it submatrixConcatenation() — which takes these two matrices as inputs, along with the coordinates specifying submatrices within A and B. This function is expected to stitch the two chosen submatrices together, forming a new one, C. Notably, the submatrices from A and B should have the same number of rows, and in the final matrix C, elements from A's submatrix should be on the left and those from B's submatrix on the right.