If the history of Zen, which I would argue is more akin to a genealogy than a history, had a telos or goal with a definitive beginning, middle, and an attainable end or goal, what might this goal be? Well, it should be obvious. The goal would be enlightenment or the same kensho (awakening to one's true nature or essence). I will go a bit further and say that Zen has no other kind of history than awakening—a very specific kind. One is on a fool's errand who would see Zen as anything other than a road to awakening. Zen does not allow for many interpretations unlike history, for example.
Be that as it may, how Zen was popularized in China during the Song dynasty, for example, is also a history, in itself, and different from the history of Zen with its telos of kensho. This history involves suspicion, namely, that something is missing which requires a kind of behind the scenes look which discovers that the Zen popularizers needed the material support of the emperor together with the literati in order to sell Zen. In other words, they had to devise clever ways to gain support. Politics, naturally, was involved. This history also leads to those Zen traditions (zong) that have been marginalized by the dominant tradition. This might include the so-called Northern School and the various other marginalized schools of Zen.
Bearing the aforementioned cook's tour in mind, we should never lose sight of what the real history of Zen is, even if we accept that it is more myth than fact (facts, too, cannot be separated from interpretation). It is all about seeing our true nature which is kensho. Zen is not a unique Asian psychology that helps us to deal with the Mitwelt, that is, how I relate to others—the social-sphere in other words. Nor is it about my psychological self, that is, how I relate to my self including my own unique personal world. This, I hasten to add, is where modern day Zennists go astray; being led to a Zen which is not really Zen since it ignores kensho (Zen teacher Brad Warner said, "I have never had a kensho experience. I hope I never do." )
Ignoring Zen's real history soon turns into ABKZ (Anything But Kensho Zen) which shows no signs of having any allegiance to the telos of Zen. This is also another history of Zen, namely, false Zen. It is the Zen of modernity which is on the road to nihilism.