That was just a joke, just like that one "French flag is white flag", you don't actually need to be that serious.
I would like to thank you first for not behaving like some of the other members here who like to call the others "stupid" and "crazy" instead of making reasonable conversation. And then, with respect, I would like to point out the false metaphor you have made:
You said that "back then Manchurian were not yet integrated into China properly". It's true -If only you admit that:
People of Chu: 「我蠻夷也,不與中國之號諡。」《史記》
Southern Song: 「其地雖要為偏方,然未有偏方之氣五六百年而不發洩者,況其東通吳會,西連巴蜀,南極湖湘,北控關洛,左右伸縮,皆足以為進取之機。 今誠能開墾其地,洗濯其人,以發洩其氣而用之,使足以接關洛之氣,則可以爭衡於中國矣,是亦形勢消長之常數也。」《宋史》
People of Wu & Shu during the Three Kingdoms:「今中國勞力,亦吳、蜀之所願。」; 「若能以吳、越之眾與中國抗衡,不如早與之絕。」
were also "not yet integrated into China properly".
We all know that their identity and "nationality" were no doubt "Chinese", but why would we call them "Chinese" even though Chu people clearly denied both the title of "China 中國" and "Chinese culture 中原文化". Because, back in those days, there wasn't a single ancient nation officially named themselves "China 中國". In other word, a country officially called "China 中國" didn't exist. During the past, "China" wasn't even a name of a state, but a title for the "rightful regime of the middleland 中原正統王朝" (that's why southern Song called Jin dynasty "China") or a geographical concept until Qing dynasty has given a new definition to the word "China 中國" :
「進入清代以後,雖然清朝直轄的18個省依然以「中國」稱之,而「天下」也保持著泛化的指稱政令實施範圍的含義。但「中國」卻有了指稱清朝疆域的用法, 「天下」與「中國」出現了重合的傾向。一個明顯的例證即是中俄《尼布楚條約》的簽訂。康熙二十八年,為了解決沙俄向東擴張而引發的邊界爭端,清朝和沙俄簽 訂了具有現代國際法水準的邊界條約----- 《尼布楚條約》。清朝依據《尼布楚條約》所立界碑全文為:「大清國遣大臣與鄂羅斯國議定邊界之碑:一,將由北流入黑龍江之綽爾納,即烏倫穆河,相近格爾必 齊河為界。循此河上流不毛之地,有石大興安以至於海。凡山南一帶,流入黑龍江之溪河,盡屬中國。山北一帶之溪河,盡屬鄂羅斯。一,將流入黑龍江之額爾古納 河為界,河之南岸屬於中國,河之北岸屬於鄂羅斯.......中國所有鄂羅斯之人,鄂羅斯所有中國之人,仍留不必遣還... ....」 很顯然,在條約中「清朝」和「中國」是可以互稱的,「中國」已經具有了一個近現代主權國家的含義。該條約的滿文、俄文、拉丁文本也都是如此。也就是說,最 遲到康熙時期,「中國」已經成為一個多民族統一國家的稱呼,中華各民族也由此開始以一個主權國家----- 中國的身份活動於世界舞台。」--《「中國」與「天下」的重合》
Nowadays 中國 is obviously an official name of your country which is found by 56 Chinese ethnic groups. In other word, these 56 Chinese ethnic groups together own the history of China and the nations found by any of these ethnics in modern China were obviously ancient Chinese nations.
I know some people will argue that: "we also have Russian in our ethnic groups, doesn't that make Russia's history our history?". These kind of people clearly don't know anything about the difference between ethnic and nationality. For instance, the founders of Yuan dynasty were the ancestors of Inner Mongolian (Golden Family), not Russian Mongolian nor Outer Mongolian, therefore Russian Mongolian and Outer Mongolian have no right to claim our Yuan dynasty. Besides, the rulers of Yuan dynasty clearly claim the successor of all the ancient Chinese dynasties, from 三皇五帝 to 唐.
Moreover, Manchurian ancestors were natives of North-East China, they were subjects of Ming dynasty and Nurhachu was even an Ming officer. The war between Ming and Qing (which were both considered as Chinese dynasties) was just one of the conflicts in Chinese history, so how could "Manchurian were not yet integrated into China properly". Besides, wouldn't you think that the Chu people who denied the identity and culture of "Chinese people" committed aggressive actions to the other warrior states is also considered as "external invasion", but we all know that the people of the 7 states has later become Han people. The invasion of Qing to Ming was indeed "external", but we all know that Han and Manchurian people are both given the Chinese nationalist nowadays. They are obviously in the "same party" and it will be unreasonable to compared our own cases with Japanese nor westerners.