Origin of "Dj" in words

I've seen a couple of references to the combination of "Dj" as part of a word, normally in names, such as Django and Ramin Djawadi. Is the "Dj" always pronounced as a "J" and where is the origin from? Seeing that Ramin has Persian descent, I'm curious if this steams from areas around Iran?

Google was next to useless, as it like to reference disc jockey sites. :) Any information is appreciated.

Update

As Dan pointed out, once the origin is know, why did English select the digraph dj?

In most cases, English didn't select the digraph "dj." The digraph is based on French orthography, like the spelling "Tchaikovsky." Although this convention originates in a foreign language, it has become part of the conventions of English spelling, and not only in names such as "Django," but also in some words such as "djinn" (also spelled "jinn").

The English sound normally represented by the letter "j" (as in juice) is called an "affricate," and can be analyzed as a combination of two parts, the "d" [d] sound of dog and the "zh" [ʒ] sound of treasure. Because it contains these two parts, the "j" affricate sound is transcribed as /d͡ʒ/ in the International Phonetic Alphabet. (The tie bar above the two letters is often omitted, so you might just see /dʒ/.)

Another affricate found in English is the "ch" sound of church. The "ch" sound combines the "t" [t] sound of time and the "sh" [ʃ] sound of shine, so it is written as /t͡ʃ/.

French uses "dj" (and ("tch") to represent an affricate sound in words from non-French languages

It is thought that French "j" and "ch" used to be pronounced as affricates, just as in English, but over time the French pronunciations lost the initial "t" or "d" part, resulting in the Modern French spelling patterns "j" = /ʒ/ and "ch" = /ʃ/.

In the modern French spelling system, /dʒ/ and /tʃ/ are represented in writing by "dj" and "tch". (Spellings similar to these are in fact used in English also in certain contexts: "tch" and "dge" are used in English to represent the "ch" and "j" sounds at the end of monosyllabic words with short vowels.)

The reason why we use French-derived spellings for some words or names of Arabic/Persian origin is probably due to historical reasons; perhaps French speakers had earlier contact than English speakers with Middle Eastern and North African languages.

"dj" appears in a few words from Latin

There are a few English words where "dj" comes from Latin spelling, such as "adjective." It's pronounced /d͡ʒ/ in these words also.

In rare cases, "dj" might have a different pronunciation

The sequence of letters "dj" does not always correspond to /d͡ʒ/.

In some languages it might just represent a consonant cluster /dj/ (pronounced "dy," like d in dog followed by y in you). For example, I believe this is the usual German pronunciation of the name "Nadja" (a variant of "Nadia"), as in Nadja Auermann.

In compound words, the letter sequence "dj" might simply represent a sequence of /d/ followed by the "j" affricate sound /d͡ʒ/. One possible example might be "bedjacket".