382 ON THE ETHNOGRAPHY AND PHILOLOGY OF THE 
ing up that river to and as far beyond its source as the Grand Coulée and the head of La 
Riviere aux Souris, thence northwest along the Coteau de Prairie, or divide, as far as the 
beginning of the Cypress Mountains, on the north fork of Milk River, down that river to 
its junction with the Missouri, thence down the Missouri to White Earth River, the 
starting-point. Formerly they inhabited a portion of the country on the south side of the 
Missouri, along the Yellowstone, but of late years, having met with great losses in that 
direction, from war-parties of the Blackfeet, Dakotas, and Crows, they have been obliged 
to abandon it, and now never go there. 
Until the year 1838 the tribe still numbered from a thousand to twelve hundred lodges, 
trading on the Missouri, when the small-pox reduced them to less than four hundred 
lodges. They were also surrounded by large and hostile tribes, who continually made 
war upon them, and in this way their number was diminished, though at the present time 
they are slowly on the increase. 
The chief rivers running through the Assiniboin country are, first, the Missouri, which 
is so well known that it needs no description here. The next is Milk River, on the north- 
west boundary, a very long and narrow stream, rising in some of the small mountains east 
of the Missouri, and lakes on the plains, runs a southwest course, and empties into the 
Missouri about a hundred miles above the mouth of the Yellowstone. Its bed is about 
two hundred yards wide, though the water seldom occupies more than one-third of that 
space, except during the spring thaws, when for a week or two it fills the entire bed, and 
even overflows the valley. It is fordable on horseback the year round, except at the time 
above mentioned, or when swollen by continued rains, and it might even be navigated 
with Mackinaw boats, when full, though the undertaking would be attended with some 
risk, owing to the large quantity of drift-wood, snags, and other obstructions. The water 
in a high stage has a white and milky appearance, caused by its flowing through beds of 
white clay, which are found along nearly the entire length of it, but more especially near 
the sources of most of its tributaries. 
The Riviere aux Tremble, or Quaking Asp River, empties into the Missouri about fifty 
miles below Milk River, is about half the length and breadth of the other, and takes its 
rise in the range of hills constituting the divide called the Woody Mountains. It is ford- 
able at all times, except during spring freshets, or when filled by heavy rains, at which 
times it could be navigated with small Mackinaw or flatboats, if floating ice and drift-wood 
would permit. 
Several creeks or small streams, of comparatively little importance, flow mto the Mis- 
souri lower down on the east side, called Porcupine, Big Muddy, Little Muddy, Knife 
River, &c., none of which contain much water. ‘These, with several small coulées, serve 
to drain the plains of the waters caused by snow and rains, and are for the most part miry, 
and only fordable on horseback in certain places where gravel bottoms are found. 
