The domains of the Golden Horde in the year 1389, before the Tokhtamysh-Timur war.  The rivers are shown in blue, the 2006 international borders in light brown, and important cities of 1389 with a black circle.  The capital of the Golden Horde, Sarai is shown with a gold star. Kiev, Moscow, Novgorod and Vilnius are shown as circles.

This map uses a Lambert azimuthal equal-area projection.
Own work. Sources used in creating this map:

Project "Geosynchrony: Atlas of World History", western borders: Nikolaev V.V. (2007) East Europe in the second half of the XIV century; eastern borders: Nikolaev V.V. (2003) Timur's state in 1370-1405.
Morgan, David (1986)  The Mongols, Butler &amp; Tanner, Frome, Somerset.
This map from Shepherd, William (1911) Historical Atlas, Henry Holt and Company, New York.
plus a review of the Tatar Encyclopedia.
MapMaster