Sorry about the picture-heavy post!
Since the topic is about XIII-XIVth centuries, I'll limit my info to that era:
Infantry-
Bulgarian XIIIth century infantry wore chain mail armor, usually reaching to the waist or hips and with either short (more common) and long sleeves.
Bulgarian chain mail
More heavily armored infantrymen wore a hard leather corselet and scale/lamellar armor in addition to the chain mail. Additional armor protection was provided by bracelets and elbow guards.
Helmets were a variety of traditional conehelmets, modified European bascinets and Byzantine style helmets, with the first being the most common. Some may have wored chain mail helmets.
Bulgarian conehelms lacked nose guards and had an aventail. The helmet were sometimes decorated with a feather.
XIth century helmets, History museum Kasanluk
The most popular shield was the round, but by the XIIIth century Bulgarians had also adopted the kite shields which were preferred over the triangular Byzantine ones.
Weapons of choice were usually swords, but also included axes and maces. Bulgar infantrymen also carried a dagger in battle. An interesting fact is that at the Battle of Adrianopole in 1205 the Bulgarians used hooks to take down the heavily armored crusaders from their horses.
A typical heavy armored bulgar infantryman carried a spear, shield, sword/mace/flail/axe and a dagger.
Bulgarian warriors defending Turnovgrad, 1393
Bulgar infantry at the Battle of Adrianopole, 1205
Cavalry-
The heavy Bulgar cavalrymen usually wore a chain mail with either short or long sleeves, on top of which lamellar/scale armor. Another option was a hard leather breastplate with steel or iron plates tied in. By the XIIIth century Bulgarian cavalry armor could possibly have included elbow guards and knee-pads made from iron, bronze or steel.
Helmets were usually the traditional Bulgarian type of the conehelm which featured an aventail. Though not so common, versions resembling the sallet were used, as well as chain mail masks.
The shields used remained mostly of the large round. Bulgar shields were made from iron or steel, with hard leather underneath. Sometimes there was a spike on the shield, allowing it to be used as a weapon.
X-XIIth century light cavalryman
The horses of the heavy cavalry had a decorative plate protecting their head and their neck was protected by a “belt” of hard leather or mail. Sometimes the area around the saddle was protected by chain mail and/or leather veil. Still, protection for the horses was usually limited to the head and neck.
Weapons of the heavy cavalry included a sword, composite bow (with a quiver of arrows) and a long spear. The traditional flag- the horsetail on the spear- was almost entirely replaced by Christian flags. Another traditional weapon, the sabers, though not uncommon was largely replaced by the sword. The spears and arrows featured different types of points.
XIIIth century chain mail mask and mace, National History Museum
Light Bulgarian cavalry was very similar to the heavy in overall appearance. The armor of the horsemen was lighter, comprised of scale or chain mail reaching to the waist/hips and helmet. Light cavalrymen carried a long wooden spear, sword/saber and a bow. Horses lacked protection.
Later Bulgarian auxiliary horsemen (c.XIVth century) wore a long gown over their armor.
The clothes, traditional Balkan, consisted of strong long leather boots, linen/wool shirt (sometimes with a skirt) with long sleeves and leather pants.
Cumans-
The early years of the Second Bulgarian Tzardom, up to the 1260’s, saw the use of many cuman mercenaries. At the time of tsar Kaloyan the cumans in the Bulgarian army reached more than 14 000. After the mongol (tatar) invasion of the territories they inhabited many cumans fled south to Bulgaria and were later assimilated in the population.
Though cumans provided a strong allied contingent to bulgarian medieval armies they were never a predominant (or even a very large) part of the bulgar army in the XIIIth cantury.
The common belief by modern western historians that bulgarian didn't resist the Ottoman invasion in the XIVth century is largely untrue. By the late 1380's after the death of tsar Ivan Alexander Bulgaria had broken up into many small tzardoms and despots, the largest of these the Turnov and Vidin Tzardoms and the Despot of Dobrudzha. Many more existed in the southern parts of Bulgaria and other areas with population with bulgarians, contested between Hungary and Serbia.
Usually these were protected by small forces of few thousand, though well equiped and trained, soldiers which were easily overrun by the ottomans.
Thousands of bulgar soldier participated in the battles of Kosovo field, the armies of Vulkshin and Uglesha, and supported the crusades in 1396 and 1443/4. Major cities and strong fortifications also resisted, usually to the last man which led to the slaughter of the resistant population.
Balkan, possibly serb armor XIIIth century
In his book "Jurney overseas in 1342" B.Brokier gives the following description to the armament of the christians [this could be either serbs or bulgars]:
"And I saw that they dress in beatiful chain-mails from a lot smaller plates than ours and simillar gloves. Such can be seen in the illustrations from the time of Julius Ceaser. Their armours reach to their hips, and in their bottom end they have attached silk. On their head they wear a round helmet, made around it [the head], which has a sharp tip half a foot long and 4 plates- one in front, one in the back and two on the sides, so that they cover the face and the back [of the wearer] from a hit with a sword, just like helmets with visors which are wored in France. They [the plates] can be bended, so a hat can be placed above the helmet, a hat of those they wera, though that is rarely seen. Many of them [the christians] wear another type of covers on the hats- nets. Sometimes they [the nets] are decorated with gold, so they cost between 40 to 50 ducats. But there are other, which cost 1 or 2 ducats, and they can resist a hit from a sabre, but the others [nets] are much stronger. This is how I saw them in the field [the christians]...they wear no breastplates, no kneepads, no other such things [from plate armour]."
as those images were taken from the book about Battle of Kalka river (1223, Mongols vs Russians) without any descriptions in the web.
. When you posted those pictures I understand your reference to western sates. 
! Thanks a lot!
