Abstract:
   Stellar orbits in galactic discs are not static but evolve through gravitational interactions with non-axisymmetric perturbations, such as bars, spirals, and giant molecular clouds. This process, known as secular evolution, efficiently redistributes stars across the disc, thereby mixing chemical signatures from their birthplaces and altering the galaxy's chemodynamical properties. Observationally, the age-metallicity distribution of the Galactic disc offers valuable insights into the Milky Way's secular evolution history. In this talk, I will present our recent findings on mapping the Milky Way's secular evolution using main-sequence turn-off stars from LAMOST. I will demonstrate how bar-driven  radial migration can reproduce observed bimodal age-metallicity sequences and the α-bimodality. Additionally, I will introduce our new chemo-chrono-dynamical model of the Galactic disc, which reconstructs its inside-out growth, metallicity evolution, and secular evolution history. Our work reveals a clear transition in radial migration strength, occurring around the epoch of the high- to low-α disc transition. Finally, by comparing these findings with Nexus simulations, I will discuss the implications of the inferred secular evolution history for the Milky Way.