I wasn't confident enough to run these three ancient genomes in Principal Component Analyses (PCA) when they were first published last year. Their SNP counts were too low for comfort. But since then I've discovered a few things about PCA projection, so here goes:
RISE595 and RISE596 are samples from present-day Montenegro dated to the Late Bronze Age and Iron Age, respectively. I haven't been able to dig up a lot of information about their archaeological contexts, but both are from Kurgan-like Tumuli burials.
If their PCA placements are correct, then I'd say they more or less resemble the samples from Bronze Age Hungary (marked on the plot as Hungary_BA). What this suggests is that their DNA, like their burial style, is in large part of steppe origin.
RISE598 is a Late Bronze Age sample from a bog burial near the present-day Lithuanian/Polish border. This individual clusters close to Unetice samples from the Czech Republic, Germany and Poland, as well as present-day Poles, which, at least to me, makes good sense.
101 ancient Eurasian genomes (Allentoft et al. 2015)