  The ultra-diffuse galaxies DF2 and DF4 in the NGC1052 group share several
unusual properties: they both have large sizes, rich populations of
overluminous and large globular clusters, and very low velocity dispersions
indicating little or no dark matter. It has been suggested that these galaxies
were formed in the aftermath of high velocity encounters of gas rich galaxies,
events that resemble the collision that created the bullet cluster but on much
smaller scales. The gas separates from the dark matter in the collision and
subsequent star formation leads to the formation of one or more dark
matter-free galaxies. Here we show that the present-day line-of-sight distances
and radial velocities of DF2 and DF4 are consistent with their joint formation
in the aftermath of a single bullet-dwarf collision, around eight billion years
ago. Moreover, we find that DF2 and DF4 are part of an apparent linear
substructure of 7-11 large, low-luminosity objects. We propose that these all
originated in the same event, forming a trail of dark matter-free galaxies that
is more than 2 Mpc long and angled 7 +- 2 degrees from the line of sight. We
also tentatively identify the highly dark matter-dominated remnants of the two
progenitor galaxies that are expected at the leading edges of the trail.
