Since these language families spread well before written language did, it's difficult to ascertain exactly what kind of culture these languages came from. Through a combination of archaeology, genetic, and linguistic analysis, some people have come up with theories with varying degrees of plausibility.

In the Indo-European case, linguists have examined extant Indo-European languages for shared roots in order to reconstruct some features of a hypothetical Proto-Indo-European language. From the words in that language that have been preserved as roots to words shared by all or most Indo-European languages, we can figure out what words were in (and which words probably weren't in) the PIE vocabulary. Thus, since there were PIE words for "snow", "tree", "deer" and "bear" we can conclude that the early Indo-Europeans lived somewhere with snow and forests. Likewise, the lack of a shared root for "ocean" suggests they didn't live near one.

Combining this linguistic evidence with genetic and archeological evidence as well as some educated guesses have led to the Kurgan hypothesis [https://en.wikipedia.org/wiki/Kurgan_hypothesis] being the most widely-accepted theory of a PIE homeland. Some have noted that the domestication of the horse may have coincided with the spread of PIE culture, and theorize that the PIE expansion may have been an early expansion of horse-riding nomadic peoples similar to the pattern that's happened many times since, often much better historically attested. Whether this was a large population transfer, enslavement and genocide, or an integration of PIE elites into existing societies is an open question with a lot of debate.

The short answer is, we don't really know for sure but there is a lot of interesting evidence, various degrees of plausibility for different theories, and ongoing debate.

Sources: https://books.google.com/books?id=R645AAAAIAAJ&pg=PA81&lpg=PA81&dq=vocabulary+in+proto+indo+european+snow&source=bl&ots=edYTTv-6ck&sig=ZjArVVJyneFJj5Y5rxvh4VYihQI&hl=en&sa=X&ved=0CEcQ6AEwBWoVChMI-ajB6vLnxwIVQRg-Ch2G5wTy#v=onepage&q=vocabulary%20in%20proto%20indo%20european%20snow&f=false https://books.google.com/books?id=R5ogAwAAQBAJ&pg=PA26&lpg=PA26&dq=vocabulary+in+proto+indo+european+snow&source=bl&ots=dicSezLMyE&sig=fhMI49L3sWewJxjA04cxB7QWd_Q&hl=en&sa=X&ved=0CEoQ6AEwBmoVChMI-ajB6vLnxwIVQRg-Ch2G5wTy#v=onepage&q=vocabulary%20in%20proto%20indo%20european%20snow&f=false