The map shows the frontier between the Central Tibet ('Outer Tibet') and Eastern Tibet ('Inner Tibet') as decided at the <a href="https://en.wikipedia.org/wiki/Simla_Convention" class="extiw" title="w:Simla Convention">1914 Simla Conference</a>, whch the <a href="https://en.wikipedia.org/wiki/Republic_of_China" class="extiw" title="w:Republic of China">Republic of China</a> rejected and the counterproposals it made.
<p>From the map legend: 
</p>
<ul><li>Bold red line: Frontier of Tibet proposed in the Simla Convention.</li>
<li>Bold brown line: Frontier of Tibet proposed by China.</li>
<li>Bold blue line: Boundary between Outer and Inner Tibet proposed in the Simla Convention.</li>
<li>Light blue line: Frontier claimed by China in 1914.</li>
<li>Pink line: Chinese proposal in 1915 for the boundary between Outer and Inner Tibet.</li>
<li>Dashed blue line: Chinese proposal in 1919 for the boundary between Outer and Inner Tibet.</li></ul>
Hugh Richardson
1945
<a rel="nofollow" class="external free" href="http://pahar.in/tibet-and-china-after-1900/">http://pahar.in/tibet-and-china-after-1900/</a>