The people in question are those who seemed to be leaders.
This would be Peter, James, and John, possibly also including a few others. Thus there were talks between leaders of the churches in Judea and the acknowledged leaders of the Gentile churches.1 The reference to Gentiles also serves to echo the call that Paul received to proclaim the gospel to Gentiles (Galatians 1:16).2
2 et ce fut d'après une révélation que j'y montai. Je leur exposai l'Evangile que je prêche parmi les païens; je l'exposai en particulier à ceux qui sont les plus considérés, afin de ne pas courir ou avoir couru en vain.