The Collaborative International Dictionary of English v.0.48:
Trek \Trek\, n. [Written also treck.] [D. Cf. Track, n.]
The act of trekking; a drawing or a traveling; a journey; a
migration. [Chiefly South Africa]
To the north a trek was projected, and some years later
was nearly carried out, for the occupation of the
Mashonaland. --James Bryce.
Great Trek, the great emigration of Boers from Cape Colony
which began in 1836, and resulted in the founding of the
South African Republic and Orange Free State.
[Webster 1913 Suppl.]