Sentence:  Though Boxhorn was working over a century before Sir William Jones, his ‘<WSD>Scythian</WSD>' is not conceptually far off the later notion of Indo-European, and his choice of term ‘<WSD>Scythian</WSD>' shows that Boxhorn was envisaging a cultural connection between the (northern) languages of the Near East and their Western European brethren, a perspicacious hypothesis that assumend some kind of ethnic drift between the two continents. 
Meaning of the word marked with <WSD> tags:  The Proto-Indo-European language.