I am a standard user of LaTeX code but I have not used much \tabular. I would like to get a table with vertical text on the left of the table. To do so, I need to merge two cells vertically. For instance, I would like the blue area with the text "Row" being on the whole height of the table. I am stuggeling for one day, I do not think it is hard, but I could not make it, even through many methods. Here is the simplest method I have found. I would be very pleased to get some help. Thank you very much.
\documentclass[9pt]{extarticle}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage[table]{xcolor}
\usepackage{colortbl}
\usepackage[titletoc,toc,title]{appendix}
\usepackage[export]{adjustbox}
\usepackage{lipsum}
\usepackage{rotating}
\usepackage{multirow}
\usepackage{enumerate}
\usepackage{pbox}
\usepackage{blindtext}
\begin{document}
\begin{tabular}{ c | c | m{60mm} | m{60mm} }
& & \multicolumn{2}{|c|}{\cellcolor{cyan} Columns} \\
& & \multicolumn{1}{|c|}{\cellcolor{yellow} Column 1}
& \multicolumn{1}{|c|}{\cellcolor{yellow} Column 2} \\
%%% The following line is related to the merge I would like to get
\multicolumn{1}{c}{\multirow{2}*{\begin{sideways}\cellcolor{cyan}Rows\end{sideways}}}
%%% End of the problem
& \multicolumn{1}{c}{\cellcolor{yellow} \rotatebox{90}{Row 1}}
& \blindtext & \blindtext \\ \hline
\multicolumn{1}{c}{} & \multicolumn{1}{c}{\cellcolor{yellow
\rotatebox{90}{Row 2}} & \blindtext & \blindtext \\
\end{tabular}
\end{document}

