  This paper continues our study of the foreground population to the Orion
molecular clouds. The goal is to characterize the foreground population north
of NGC 1981 and to investigate the star formation history in the large Orion
star-forming region. We focus on a region covering about 25 square degrees,
centered on the $\epsilon$ Orionis supergiant (HD 37128, B0\,Ia) and covering
the Orion Belt asterism.
  We used a combination of optical (SDSS) and near-infrared (2MASS) data,
informed by X-ray (\textit{XMM-Newton}) and mid-infrared (WISE) data, to
construct a suite of color-color and color-magnitude diagrams for all available
sources. We then applied a new statistical multiband technique to isolate a
previously unknown stellar population in this region.
  We identify a rich and well-defined stellar population in the surveyed region
that has about 2\,000 objects that are mostly M stars. We infer the age for
this new population to be at least 5\, Myr and likely $\sim10$\,Myr and
estimate a total of about 2\,500 members, assuming a normal IMF. This new
population, which we call the Orion Belt population, is essentially
extinction-free, disk-free, and its spatial distribution is roughly centered
near $\epsilon$ Ori, although substructure is clearly present.
  The Orion Belt population is likely the low-mass counterpart to the Ori OB Ib
subgroup. Although our results do not rule out Blaauw's sequential star
formation scenario for Orion, we argue that the recently proposed blue streams
scenario provides a better framework on which one can explain the Orion star
formation region as a whole. We speculate that the Orion Belt population could
represent the evolved counterpart of an Orion nebula-like cluster.
