The ram that you saw with the two horns stands for the kings of Media and Persia.

In the first year of Darius ¹  son of Ahasuerus, ²  who was of Median descent and who had been ³  appointed king over the Babylonian ⁴  empire –

Now let the king issue a written interdict ¹  so that it cannot be altered, according to the law of the Medes and Persians, which cannot be changed. ² 

So they approached the king and said to him, ¹  “Did you not issue an edict to the effect that for the next thirty days anyone who prays to any god or human other than to you, O king, would be thrown into a den of lions?” The king replied, “That is correct, ²  according to the law of the Medes and Persians, which cannot be changed.”