This isn't a Borges quotation, but it sounds like one:

3. Pollsmoor Prison, South Africa
An elaborately structured prison gang called the Numbers Gang — and its subgangs, the 26s, 27s and 28s — plagues the overcrowded Pollsmoor. The Numbers have operated for decades throughout South African prisons, with baroque hierarchies and rituals; its power is so widespread that years of attempts to eradicate the gang have failed.

via Prison Planet -