\documentclass{book}

\usepackage{graphics}
\usepackage{amsmath}
\usepackage{TikZ}
\usepgflibrary{arrows.meta} % LATEX and plain TEX and pure pgf
\usepgflibrary[arrows.meta] % ConTEXt and pure pgf
\usetikzlibrary{arrows.meta} % LATEX and plain TEX when using Tik Z
\usetikzlibrary[arrows.meta] % ConTEXt when using Tik Z
\usetikzlibrary{datavisualization}
\usetikzlibrary{datavisualization.formats.functions}
\usetikzlibrary{datavisualization.polar}
%\usepackage[active,tightpage]{preview} \PreviewEnvironment{tikzpicture}\setlength\PreviewBorder{0mm}
\usetikzlibrary{calc}
\usetikzlibrary{math}
\usetikzlibrary{intersections}
\usepackage{xepersian}



\renewcommand{\d}{\mathrm{d}}

\settextfont{Yas}

\begin{document}

\begin{tikzpicture}
\filldraw [fill=gray!10]
(5.44, 1.37) .. controls (4.6, -0.454) and (2.2, 0.15) .. (2.0, 0.814) --
(2.0, 0.814) .. controls (1.83, 1.55) and (2.25, 1.55) .. (2.7, 2.19) --
(2.7, 2.19) .. controls (3.15, 2.93) and (2.75, 3.45) .. (2.95, 3.9) --
(2.95, 3.9) .. controls (3.12, 4.365) and (3.4, 4.7) .. (4.1, 4.13) --
(4.1, 4.13) .. controls (4.43, 3.9) and (4.665, 3.15) .. (5.22, 2.71) --
(5.22, 2.71) .. controls (5.4, 2.55) and (5.75, 2.15) .. cycle;

%dx vector
\draw[very thick, -Stealth] (3.7, 2.2) -- (4.38, 4.74);
\node at (4.5, 1.9) [] {$ \mathbf{x} = \boldsymbol{\gamma} (\xi) $};
\node at  (5.15, 5) [] {$ \d\mathbf{x} = \boldsymbol{\gamma}' \d\xi $};
\node at (3.6, 0.5)[] {$ \Omega_0 $};
\node at (3.5, -0.3)[] {$\text{لحظۀ $t $}$};
\end{tikzpicture}
\end{document}