IndoEuropean
It turns out that most of the major language families are related into one superfamily, referred to as Indo-European. They are associated with various groups of migrants that appeared during the BronzeAge, around 2000-1600 BC. Huge amounts of information about PIE lexicon and grammar have been inferred. Discussion about actual proto-IE culture has been stalled, though, by its association with the racist doctrines of NaziGermany.
The various subgroups of Indo-European include:
CelticLanguages
ItalicLanguages - including LatinLanguage and its descendants, the RomanceLanguages
IllyrianLanguages
GreekLanguage
AnatolianLanguages
IndoIranianLanguages, e.g. SanskritLanguage