the high-resolution molecular line data, inner environments of at least two sub-regions W33 A and W33 Main have been reported in the literature [@galvan10; @jiang15; @maud17]. To explain star formation (SF) activity in the direction of W33 A, @galvan10 proposed a triggered SF scenario by filamentary convergent gas flows from two different velocity components. In the direction of the W33 complex, @kohno18 reported three velocity components at 35, 45, and 58 km s$^{-1}$, and found the signatures of the collision between two clouds at 35 and 58 km s$^{-1}$. They assumed these clouds at a distance of $\sim$2.4 kpc. Considering this argument, a collision scenario was proposed to explain the massive SF in the W33 complex [see @kohno18 for more details]. @messineo15 also mentioned the possibility of sequential SF and feedback in W33. However, such study is not extensively carried out in W33. To our knowledge, earlier observational works toward W33 are restricted up to an area of 15 pc $\times$ 15 pc [see Figure 1 in @kohno18], and its large-scale environment (i.e., $>$ 35 pc $\times$ 35 pc) is yet to be examined.

In this context, Figure \[fig1\]a displays a large-scale area ($\sim$1$\degr$.1 $\times$ 0$\degr$.815) containing the W33 complex 