Final answer:
In the first battle between the army of Tomiris and the Persians, the Persians were victorious as they caught Tomiris's forces off guard during the night.
Step-by-step explanation:
The outcome of the first battle between the army of Tomiris and the Persians is that the Persians won the battle. The Persians attacked the Sakas at night when they were unprepared and sleeping, leading to the complete destruction of Tomiris's army. This initial victory for the Persians was countered in a second battle, where they suffered a loss, and their king was killed.