Mongolian Swordsmen are the sword-armed Mongol troops you meet most often on Tsushima and Iki. They attack fast in long combos, so the Stone Stance, which you have from the Prologue, is the tool for breaking them.
They try to swamp you with speed. One combo landing clean can take a big piece of your health, and the tougher ones lunge in to close the gap. Later tiers coat their blades in fire. The basic grey swordsman has little beyond a string of short swings.
Switch to Stone Stance and lead with heavy attacks to break their guard, then finish with light attacks or the held Piercing Strike. Parry their combos where you can. Unyielding Sword Parry lets you parry the blue-glint unblockables the dual-wielders throw.
Bandits
Bandits are the island's common criminals, attacking villagers, Mongols, ronin and Jin alike. They are a secondary enemy in Izuhara during Act 1, poorly armed and predictable, but reckless enough to hurt you.
Eagle Tribe
The Eagle Tribe is the Mongol force that has taken Iki Island, led by the shaman Ankhsar Khatun, called the Eagle. They are the main enemy of the Iki Island expansion, and their purple-uniformed troops bring units you never see on Tsushima.
Mongol Archers
Mongol Archers are the bowmen at the back of every Mongol group. They are fragile up close but chip away at you from off-screen, so kill them early or close the distance fast.
Mongol Eagle Bearers
Mongol Eagle Bearers are archers or swordsmen paired with a trained eagle that circles overhead and spots you. They fight like normal soldiers, but the bird makes sneaking up on their group much harder.