The most complete survey of the objective, academic work on this area can be found at
http://www.calstatela.edu/faculty/asolomi/images/Afro-ArgReview.pdf
An interesting statistic from this survey: "
In 1869, the proportion of the national population who were of African origin was registered as 26.1%; in 1895, it was 1.8%"'.
This means that from over twice the population of blacks in the present USA, there was a massive change to almost negligible. There is no "documentary evidence", but the obvious answer is staring us in the face. In a country where INDEC can say the the present inflation rate is only 1 to 3 %, when we know from being here that it is at least 25%, we know that it is easy to hide the truth. There was a concerted and public action to annilihate the black Argentineans in the late 18th Century. There wer no significant wars from 1870 on (Argentina's only significant war from Independence to the Falklands War was the War of the Triple Alliance in which mainly Paraguayans died and which was bascally over by 1869).
Obviously the only logical conclusion is that all-out genocide was started by President Sarmiento (called "the great educator" here for his public school programs) who hated blacks and feared that the blacks here would be encouraged to be assertive after the American Civil War. He wrote in his diary in 1848 during a visit to the USA after observing the complications that the slavery issue raised in the US at that pre-civil- war time, and that Argentina's solution would only be the death of the blacks. When he was President of Argentina in the 1870's, he allowed and encouraged the paramilitaries to do their worst in a way that the KKK (and the Nazis) could only dream of. Many Gaucho ballads from the 1870's and 1880's joyfully talk about killing blacks as sport practiced with impunity. One of the key passages of
Martin Fierro, written in 1872 and considered the national book of Argentina, consists of two such encounters. That they may have been protected by the economy is irrelevant, the laws arenot even in force in Argentina now.
The excuses of war or disease or assimilation intothe general population or swamped by immigrants are completely laughable, they make no logical sense whatsoever. The Argentine education ststem has tried to eliminate Black history in Argentina. We know that as much as half of General San Martin's liberation army in the 1810's were black slaves, and that the celebrated Sargento Cabral who saved San Martin during a battle was black, but the history books here are silent on this point. The southern US states had fromal means of discrininating and eliminating blacks after the civil war, and they did obviously not come close to what Sarmiento and his cohorts did in the late 19th century.
This is just another example of studied ignorance that we see in Argentina every day.
I love Argentina, and I am not black, but it is amazing how truth has / is completely ignored and suppresed here.