As mentioned above he (that is, Moses) is the emphatic element in this sentence.

If the strictly temporal aspect of the participle performing (miracles and wonders) is stressed, then it technically means action which was done before Moses led the people out of Egypt. For this reason it is best to take the participle purely in its instrumental aspect, that is, “by performing miracles and wonders.” The King James Version translation (“after that he had showed wonders and signs in the land of Egypt, and in the Red sea, and in the wilderness forty years”) is a correct translation if the temporal aspect of the participle is emphasized; but this makes poor sense, inasmuch as all these actions must be looked upon as happening prior to the main verb led the people out. The Jerusalem Bible attempts to bring out the temporal notion of the participle, but the translators seem to have gone too far in rearranging it, “It was Moses who, after performing miracles and signs in Egypt, led them out across the Red Sea and through the wilderness for forty years.”

If one interprets performing miracles and wonders as being primarily instrumental, that is, “the means by which Moses was able to lead the people out of Egypt,” then one can combine much more effectively Egypt, the Red Sea, and the desert. However, it is necessary in many languages to translate “in the country of Egypt,” “along the Red Sea,” and “in the desert,” with desert often rendered as “uninhabited lands.”

Note, however, that the temporal expression for forty years must be associated only with what was done in the desert. In some languages it is necessary, therefore, to introduce a verbal expression which would refer to the performing of miracles and wonders, for example, “he continued to perform miracles in the desert for forty years.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on The Acts of the Apostles. (UBS Handbook Series). New York: UBS, 1972. For this and other handbooks for translators see here .