Deep geek post here just for the search engines. If you're playing Knights of the Old Republic and you're on Tatooine and you try to enter the Sand People Enclave and you're told "your entire party has been killed" with no explanation, you've hit a bug. Explanation below.
The bug seems to be triggered by faulty logic around wearing the sand people robes. In certain circumstances the robes are removed from you; teleporting to the Ebon Hawk, for instance. When this happens the robes get glitched. If you put the robes on again and try to enter the Enclave it fails and you get killed without explanation.
The workaround I used was to take the robes off. This got me past the glitch. My "looks like sand people" bit was still set, so I was able to enter the enclave without being attacked. Another option is to go back to before you ever put the robes on and then only put them on at the last minute. You may still hit the glitch though. A final option is to give up on the disguise entirely and just roll in.