==Here's what the Histories say on the Qiang== 

 I did a little snooping around and found additional information on the Qiang people. The information below comes from Chinese histories (i.e. the Book of Later Han and Zizhi Tongjian). Apparently, the Qiang people of the Hexi Corridor commanderies (i.e. Zhangye, Wuwei, Jiuquan, and Dunhuang) were sent in 106 CE to Kashgar to relieve a siege against Ren Shang, who was then the head of Han's Protectorate of the Western Regions. The siege was lifted by the time the Qiang arrived. However, these Qiang troops, led by Liang Qin, were sent to garrison a city in the oasis state of Kucha. So yes, anonymous IP, the Qiang WERE SENT to the Tarim Basin. In fact, after Liang Qin and his Qiang troops entered Kucha, the inhabitants rebelled against them, a rebellion which the Qiang under Liang's command were charged with quelling. 

 Now, as for the Qiang people who rebelled in the Hexi Corridor in 107 CE, they were actually a different group of Qiang people from Jincheng, Longxi, and Hanyang commanderies in what is now southeast Gansu province. This group of Qiang people were supposed to reinforce the Protector General Duan Xi as he pulled out of the Tarim Basin. Just as Rafe de Crespigny asserts, these Qiang were uncertain about how long they would have to serve in the Tarim Basin, so they rebelled against Han to avoid serving as conscripts. Afterwards, Liang Qin and his Qiang troops returning from the Tarim Basin fought these rebelling Qiang people from Jincheng, Longxi, and Hanyang and defeated them. Liang Qin's forces killed some eight to ten thousand of them. Thus, your assertion about Qiang fighting Qiang is not incorrect, but you are entirely incorrect about the reason WHY this group of Qiang decided to rebel. An assertion of Crespigny's that you rejected, even though he is a respected sinologist and you are some random guy using a bunch of public computers in Singapore (that's right, I check IP addresses).  

 Anyways, here's my evidence: 

 Zizhi Tongjian chapter 49: 

 (孝殤皇帝延平元年/AD 106) 
 ... 詔以北地梁慬為西域副校尉。慬行至河西，會西域諸國反，攻都護任尚於疏勒；尚上書求救，詔慬將河西四郡羌，胡五千騎馳赴之。慬未至而尚己得解，詔征尚還，以騎都尉段禧為都護，西域長史趙博為騎都尉。禧、博守它乾城，城小，梁慬以為不可固，乃譎說龜茲王白霸，欲入共保其城；白霸許之，吏民固諫，白霸不聽。慬既入，遣將急迎段禧、趙博，合軍八九千人。龜茲吏民並叛其王，而與溫宿、姑墨數萬兵反，共圍城，慬等出戰，大破之。連兵數月，胡眾敗走，乘勝追擊，凡斬首萬餘級，獲生口數千人，龜茲乃定。... 

 (孝安皇帝永初元年/AD 107) 
 ... 西域都護段禧等雖保龜茲，而道路隔塞，檄書不通。公卿議者以為「西域阻遠，數有背叛，吏士屯田。其費無已。」六月，壬戌，罷西域都護，遣騎都尉王弘發關中兵，迎禧及梁慬、趙博、伊吾盧、柳中屯田吏士而還。 

 初，燒當羌豪東號之子麻奴隨父來降，居於安定。時諸降羌布在郡縣，皆為吏民豪右所徭役，積以愁怨。及王弘西迎段禧，發金城、隴西、漢陽羌數百千騎與俱，郡縣迫促發遣。群羌懼遠屯不還，行到酒泉，頗有散叛，諸郡各發兵邀遮，或覆其廬落；於是勒姐、當煎大豪東岸等愈驚，遂同時奔潰。麻奴兄弟因此與種人俱西出塞，先零別種，滇零與鍾羌諸種大為寇掠，斷隴道。時羌歸附既久，無復器甲，或持竹竿木枝以代戈矛，或負板案以為楯，或執銅鏡以象兵，郡縣畏懦不能制，丁卯，赦除諸羌相連結謀叛逆者罪。 
 ... 

 詔車騎將軍鄧騭、征西校尉任尚將五營及諸郡兵五萬人，屯漢陽以備羌。... 

 (孝安皇帝永初二年/AD 108) 
 春，正月，鄧騭至漢陽；諸郡兵未至，鐘羌數千人擊敗騭軍於冀西，殺千餘人。梁慬還，至敦煌，逆詔慬留為諸軍援。慬至張掖，破諸羌萬餘人，其能脫者十二三；進至姑臧，羌大豪三百餘人詣慬降，並慰譬，遣還故地。... 

 Hou Han Shu chapter 47 (biography of Liang Qin 梁慬): 

 延平元年拜西域副校尉。慬行至河西，會西域諸國反叛，攻都護任尚於疏勒。尚上書求救，詔慬將河西四郡羌胡五千騎馳赴之，慬未至而尚已得解。會征尚還，以騎都尉段禧為都護，西域長史趙博為騎都尉。禧、博守它干城。它干城小，慬以為不可固，乃譎說龜茲王白霸，欲入共保其城，白霸許之。吏人固諫，白霸不聽。慬既入，遣將急迎禧、博，合軍八九千人。龜茲吏人並叛其王，而與溫宿、姑墨數萬兵反，共圍城。慬等出戰，大破之。連兵數月，胡觿敗走，乘勝追擊，凡斬首萬餘級，獲生口數千人，駱駝畜產數萬頭，龜茲乃定。而道路尚隔，檄書不通。 

 歲余，朝廷憂之。公卿議者以為西域阻遠，數有背叛，吏士屯田，其費無已。 

 永初元年，遂罷都護，遣騎都尉王弘發關中兵迎慬、禧、博及伊吾盧、柳中屯田吏士。 

 二年春，還至敦煌。會觿羌反叛，朝廷大發兵西擊之，逆詔慬留為諸軍援。慬至張掖日勒。羌諸種萬餘人攻亭候，殺略吏人。慬進兵擊，大破之，乘勝追至昭武，虜遂散走，其能脫者十二三。及至姑臧，羌大豪三百餘人詣慬降，並尉譬遣還故地，河西四郡復安。 

 Hou Han Shu chapter 87 (on the Western Qiang): 

 東號子麻奴立。初隨父降，居安定。時諸降羌布在郡縣，皆為吏人豪右所徭役，積以愁怨。安帝永初元年夏，遣騎都尉王弘發金城、隴西、漢陽羌數百千騎征西域，弘迫促發遣，腢羌懼遠屯不還，行到酒泉，多有散叛。諸郡各發兵儌遮，或覆其廬落。於是勒姐、當煎大豪東岸等愈驚，遂同時奔潰。麻奴兄弟因此遂與種人俱西出塞。 

 先零別種滇零與鐘羌諸種大為寇掠，斷隴道。時羌歸附既久，無復器甲，或持竹竿木枝以代戈矛，或負板案以為楯，或執銅鏡以象兵，郡縣畏懦不能制。冬，遣車騎將軍鄧騭，征西校尉任尚副，將五營及三河、三輔、汝南、南陽、穎川、太原、上黨兵合五萬人，屯漢陽。明年春，諸郡兵未及至，鐘羌數千人先擊敗騭軍於冀西，殺千餘人。校尉侯霸坐觿羌反叛征免，以西域都護段禧代為校尉。 

 I believe this settles it once and for all. And I believe you owe me a huge apology for suggesting that I should "crawl away instead quoting useless stuffs here that don't matter at all". Yeah, right. Quoting useless stuff like Rafe de Crespigny and Yu Ying-shih. If that's not good enough for you, here are the original sources they used.