[Stalker]

In my opinion, a very interesting alternation:
Romans learned stirrup at Marcus Aurelius' time before Markoman war. Early introduction of heavy cavalry instead of cataphracts into cavalry tactics would make the transitional period to Middle Ages more smooth because getting rid of restless independent Germanic tribes in continental Europe could have presented Rome some more quiet centuries to cope with the crisis of economy. But having smashed Germans to dust, and extending its borders from Rein to Vistula, Rome would have come to face another barbaric unions - Slavs and Baltics
I guess, Dark Ages were unavoidable in any case but is there a chance that in the case mentioned above, human knowledge and culture accumulated by Rome would have lost less then in our history?