DISCLAIMER: I'm more than a little biased where this topic is concerned. However, I'm also rather knowledgeable for precisely that reason. Hopefully this answer meets this subreddit's standards. I'll be happy to address any further questions.

Since the prior century, Armenia had been split into two - the West was ruled by the Ottomans, and the East by the Russian Empire. As well as the massive linguistic and cultural impact this split between two empires had, it also meant that a small part of historical Armenia (what currently makes up modern Armenia, it is not carved out of the Armenian lands Turkey currently occupies) was shielded from Turkish attempts to eradicate the Armenians in the Genocide. There was therefore a sizeable amount of Armenians untouched by the Genocide, as well as a number of refugees who fled east.

Then came the Russian Revolution. As the Russian Empire fell apart and was engaged in civil wars focused around Soviet-held cities like Petrograd and Moscow, Armenia was, for a time, independent. This "First Republic" won a number of victories against Turkish invasion forces, and at the close of WWI the Treaty of Sevres actually demanded that the defeated Turkey hand over the Ionian Coast and Constantinople to Greece and historical Armenia to the new Armenian state. Neither agreement was honoured for long, and the USSR took back Armenia and made it a Soviet state.

While living under Soviet rule can hardly have been a pleasant experience (as incidents such as Stalin's rule and the easily preventable catastrophe of the Armenian earthquake illustrate), the "Second Republic" phase was at least useful in helping Armenia modernise and was certainly preferable to utter destruction. After the USSR broke down, Armenia emerged in its Third Republic stage, and has remained so for the past 23 years.