I found the following on Wikipedia.
Integration over more general domains is possible. The integral of a function $f$, with respect to volume, over an $n$-dimensional region $D$ of $\mathbb{R}^{n}$ is denoted by symbols such as: $${\displaystyle \int _{D}f(\mathbf {x} )d^{n}\mathbf {x} \ =\int _{D}f\,dV.}$$
What does $d^n\textbf{x}$ mean in this context? Is it a abbreviation for $dx_1dx_2 \dots dx_n$?