Our goal is to better understand the origin and the star-formation history of regions NGC 6334 and NGC 6357. We focus our study on the young stars (young stellar objects and OB stars) kinematics in both regions using mainly Gaia-DR2 data. For both regions we compiled OB stars and young stellar objects catalogues from literature and we complemented them using VPHAS+ DR2 and Spitzer IRAC/GLIMPSE photometry catalogues. A cross-match is performed with the Gaia-DR2 catalogue in order to obtain the parallax and transverse motion information. We confirm that NGC 6334 and NGC 6357 are in the far side of the Saggitarius-Carina arm at a distance of 1.76kpc. For NGC 6357, OB stars show strong clustering and ordered star motion with Vlon~-10.7km/s and Vlat ~3.7km/s while for NGC 6334, no significant systemic motion is observed. The OB stars motions and distribution in NGC 6334 suggest to classify it as an association. Ten and two runaway candidates can be related to NGC 6357 and NGC 6334, respectively. The spatial distributions of the runaway candidates in and around NGC 6357 favor a dynamical (and early) ejection during the cluster(s) formation. Because such stars are likely to be ejected during cluster's formation the fact of not observing as many of such stars towards NGC 6334 suggest different formation conditions than for NGC 6357.

Cone search capability for table J/A+A/642/A21/tableb1 (Astrometric parameters for 135 OB stars)