  We review our current knowledge of the population of high-redshift sub-mm/mm
galaxies, with particular emphasis on recent results from the SCUBA HAlf Degree
Extragalactic Survey (SHADES). All available evidence indicates that these
objects form the high-redshift, high-luminosity, high-mass tail of the dusty
starforming galaxy population revealed at lower redshifts and luminosities by
Spitzer. Current theoretical models of galaxy formation struggle to reproduce
these extreme objects in the numbers indicated by current surveys.
