After I Transmigrated, the Authorities Sent Me Twins

(System + twins + ordinary country folk + multiple heroines + invincible in the later stages + alternate history) After transmigrating to ancient times, into a parallel version of the Zhou Dynasty, the protagonist gets a System and grows stronger over time. There are many female characters, and they all get plenty of screen time. He focuses on building strength in the early stages and becomes invincible later on. A human tank, a walking natural disaster.