Sylvain pathed the connection between Afro-descendants and Africans and became a representative for these groups that were colonized by France.

In 1887, he finished his studies in Paris at the Collège Stanislas, then attended law school, where he obtained his license and then his doctorate.

Supported by his country that appoints the officer of Marine and secretary to the embassy in London, Sylvain founded in Paris in 1890 a weekly committed against French colonialism, La Fraternité (which appeared until 1897).

In 1897, Sylvain staying in Ethiopia became the aide-de-camp to Emperor Menelik II, who defeated the Italians at the Battle of Adwa.

Sylvain represented both Ethiopia and Haiti at the 1900 Pan-African Conference held in London, and was appointed as honorary president of the Pan African Association.