Abstract: In the past decade, our understanding of the galaxy population in the first 4 billion years of cosmic history (z>2) has improved significantly, thanks to the increasing ability to construct comprehensive snapshots (in time) from z=4 (when the universe was ~1.5 billion years old) to z=2. I will summarize our current knowledge of the (massive) galaxy population at z=2-4, with an emphasis on the results from the NEWFIRM Medium-Band Survey, a large NOAO/Yale program which uses medium band-width filters in the near-infrared to obtain well-sampled spectral energy distributions and high-quality photometric redshifts at z>1.5 over 0.5 square degree. I will present recent results from the UltraVISTA and NMBS-II, and preliminary results from on-going follow-up spectroscopic programs.