How do globular clusters form? Can such massive concentrations of stars arise from gas clouds alone, or is a central black hole required?

Globular cluster M80, like other globulars, likely formed from condensing clouds of interstellar material.

The Hubble Heritage Team (AURA/STScI/NASA)

For such a cluster to form, huge amounts of interstellar material must compress into a tiny volume very quickly.

Old globular clusters, such as those living in the halo of the Milky Way, certainly host stellar-mass black holes. However, such black holes are the products of stellar evolution within their clusters and do not influence their clusters’ formation.