Armour and Heat
Looking at the map on page 28 of the rule book, all the provinces south of the North India-Lower Yángzi line have a humid subtropical climate. The omnipresent daytime heat and humidity affect the inhabitants' choice in armour: people in these areas avoid carrying any piece of armour whose Burden is Moderate (or heavier). Should a player character insist on carrying such a piece of armour, he must succeed at a Stamina roll every time he is doing any activity more tiring than walking. A failed roll results in the character losing 1 general hit point of damage because of fatigue. A fumble results in the character passing out with exertion (on top of the hp loss).