(A) Schematic velocity field and GC Arms I and II, and Sgr-B projected on the galactic plane. (B) Schematic longitude–velocity diagram of Sgr-B2, B2, Sgr-B molecular complex. Red colour represents |${v_{\rm LSR}} \sim 60$|–70 km s|$^{-1}$|⁠, green |$\sim 30$|–50 km s|$^{-1}$|⁠, and blue |$\sim 20$|–30 km s|$^{-1}$|⁠. The grey line is the GC Arm I on which Sgr-B1 and B2 are located. The |$\sim 35$| km s|$^{-1}$| ‘hole and ring’ (Bally et al. 1988) is here interpreted as the slice of the bubble/cylinder at the velocity. (C) Dual-side compression (DSC) of molecular cloud by the Galactic shock wave and stellar feedback. Red arrow from right top represent compression perpendicular velocity |$({V_{\rm rot}}-V_{\rm pattern}) \sin \ p\sim 30$| km s|$^{-1}$|⁠, red arrow from left bottom. (D) meerkat continuum map in red with black contours at 1 mJy beam|$^{-1}$| overlaid on |$^{13}$|CO 35 km s|$^{-1}$| channel map in green (as Fig. 2 bottom left). The -molecular cloud in green approximately represents cross-section of the bow-shock cone along the straight line in panel (C), while the continuum emission is the integration along the line of sights. (Color figures online.)