The phrase "powerful empire" is correct and usable in written English.
You can use it to refer to a country or kingdom which has a lot of strength or power. For example, "The Roman Empire was a powerful empire that spanned across Europe for centuries."
For a period of barely 100 years, The Netherlands boasted the most powerful empire in the world – a power driven by markets rather than privilege.
The people who, according to legend, emerged from the Island of the Sun on Lake Titicaca, extended their power over the barren altiplano and across the Andes to create the most powerful empire in the Americas.
THE most powerful empire ever seen extends its influence throughout the planet.
Between them, over time, the Romanovs established the modern world's largest and most powerful empire.
This immensely powerful empire was responsible for forging the present day cultures of the whole region.
I feel I am standing on the flexing muscle of the most powerful empire in history.
In other words, as time goes on, weak empires lose their colonies and more powerful empires occupy these colonies and enhance their power.
SUGAR and spice motivated many an explorer, and the voyages of discovery that resulted from European demand for these products were the basis for building powerful empires.
There are beautiful towns, too, reminders of when the country was part of one of Europe's biggest and most powerful empires.
Ever since the early campaigns of the prophet Mohammed, small groups of desperate men, utterly careless of their own safety and the lives of others, have shaken powerful empires.
Bihar had some of the country's sickest, poorest and shortest-lived people in India, a dismal catalog for a state that in its glory days, a few millennia ago, was home to one of South Asia's most powerful empires and the place where the Buddha reached enlightenment.
