The original scan of this photo has cut off the name of the horse, but it’s fairly legible even so, and the following page is able to identify this horse as Osman III: As you can see, he was sired by Aslan and out of the mare Ablulu (Aslan x Hazam), born Oct. 27th 1890. The article this photo was found in dated to 1902 at the very earliest, making this horse 12 years or younger at the time of it being taken. Osman III was owned by Nathan Miers Cox. Interestingly enough, in this same series of articles, Aslan is said to have been imported in 1871, and the same paragraph indicates that he was around 29 years old in 1896 – putting his date of birth at around 1867. Both of these dates are different than the previous information listed for Aslan, but the proximity suggests that we may be on the right track with those dates.
I am posting this on behalf of Miguel, who is quite knowledgeable of the history of the Arabian horse breed in Chile, where he tells me that he believes the Chilean registry is the oldest of all those in South America. The Chilean registry includes Peru, and is said to have begun in in 1872, the details of which you will find below.