When speaking about hyperbolic groups/spaces, one usually refers to Gromov's monograph Hyperbolic groups for their introduction. However, coarse notions of hyperbolicity can be found in some of his earlier texts, such that Infinite groups as geometric objects and Hyperbolic manifolds, groups and action. Also, among the (many) equivalent definitions of $\delta$-hyperbolic spaces, one of them refers to Rips' condition, suggesting that E. Rips played some role here.
Hence my question:
What is the prehistory of Gromov-hyperbolic spaces/groups?
Here, "prehistory" refers to "before Gromov's monograph".
Edit: I should specify that I am not looking for the historical motivations of the definition, but the origins of the definition itself. How did the definition emerge?