Having aspects of your job description taken away from you...

I am a junior in my company. We do private equity raises. Part of my job coming on was to develop a new sales channel, by recruiting a specific type of financial professional to sell for us. This has been going quite well. I have developed all the materials, training, etc. and am gaining traction. My understanding was that this was my baby across the geographic regions we focus on, for the long term. Now I am learning that two more senior guys who are new hires are being given the responsibility of doing this work in their specific regions, along with their other duties. I am sharing my materials with them. Is it unreasonable for me to feel like my toes are being stepped on? In the short term, it's really of no significance, because it will take me a while to get to the point where I am ready to begin targeting their geographic territories. But I feel like they have other areas they could be working, not the specific niche I was hired to target, and like I am not being given a fair opportunity to prove myself. Is this a legitimate concern? Or do I just keep working until my territory pushes up against theirs, and at that point find out whether I will be taking over their territory in this market, or will be re-tasked? For the record hiring is rather opaque in this company and no one has actually told me these guys are doing this and how it impacts me. I'm just receiving random emails here and there from them telling me that they have a meeting or they need my materials.

Valid question, but impossible. This last week has been a series of successes, and it's not that I'm being cut out in my area, just cut out of areas I would have naturally moved into.

I think I'll just keep working at it and not sweat it. The senior guys are exactly that, senior, and I can probably get more from working actively with them than by trying to separate myself.