The explanation of DOM (in Portuguese) in MDN is good. Taking excerpts from there:
The Document Object Model (DOM) is a programming interface for HTML, XML, and SVG documents.
[...]
Although the DOM is often accessed using JavaScript, it is not a part of the JavaScript language. It can also be accessed by other languages.
There's another interesting article at W3C where it says:
As a W3C specification, one important objective for the Document Object Model is to provide a standard programming interface that can be used in a wide variety of environments and applications.
ie in summary terms "can be used in a variety of environments and applications".
In addition to the OMG IDL specification, we provide language bindings for Java and ECMAScript.
If we consider that in the browser it is common to use JavaScript to manipulate the DOM, this is not the only language that can manipulate the DOM, in the desktop or mobile browser.