Large-N D-brane holography is one of our most promising candidates for a non-perturbative definion of string theory. A myriad of developments in the last thirty years (such as Susskind-Uglum open string edge modes, holographic subregion duality, entanglement wedge reconstruction, and entanglement islands among many others) have demonstrated that the entanglement structure of string theory is intimately related to the emergence of semiclassical spacetime and - in particular - the UV structure of black hole microstates. Matrix Quantum Mechanics (MQM) is particularly important toy model in this context, as it is suspected to be a blueprint for how locality emerges on the sub-AdS lengthscale and the compact dimensions in the bulk of AdS/CFT. In this talk we will review recent developments on entanglement in matrix quantum mechanics and how geometric subregions in the stringy bulk can emerge from non-geometric color partitions of the quantum mechanical boundary.